JP7270185B2 - Temperature gradient forming device and Seebeck coefficient calculation method - Google Patents

Description

The present invention relates to a temperature gradient forming device and a Seebeck coefficient calculation method.

Today, in the field of materials with nanomaterials as a keyword, there is a demand for techniques for evaluating materials with nanoscale resolution. For example, in the field of research on nanoscale thermal management, it is required to study how heat is transferred locally in thermoelectric materials.

Conventionally, for example, Non-Patent Document 1 discloses a technique for measuring the Seebeck coefficient of a nanoscale thermoelectric material.

“Seebeck Coefficient Measurement by Kelvin-Probe Force Microscopy”, H.Ikeda, F. Salleh, K. Asai, Journal of Automation, Mobile Robotics & Intelligent System, volume 3, N.4 2009

As described above, the local thermal properties of a thermoelectric material, such as the voltage distribution and temperature distribution of the thermoelectric material, provide necessary information for developing thermoelectric materials. The technique of Non-Patent Document 1 is intended to measure the potential difference between two points where the temperature is constant in each region on the heating side and the heat dissipation side, and the Seebeck coefficient as a whole is obtained from these two points. Not too much. That is, Non-Patent Document 1 does not disclose an apparatus or method for obtaining local thermal properties (physical property distribution) of a measurement target.

SUMMARY OF THE INVENTION The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a temperature gradient forming apparatus and a Seebeck coefficient calculation method capable of obtaining local thermal properties of an object to be measured.

In order to solve the above-described problems, a temperature gradient forming apparatus according to the present invention is a sample having a substance to be measured, which is a scanning target of a scanning probe microscope, and comprises a heating region, a cooling region, the heating region and the a cooling region and a temperature transition region in which the substance to be measured is exposed at least corresponding to the scanning range of the scanning probe microscope; and holding the sample against the scanning probe microscope. a sample holder that locally forms a temperature gradient in the temperature transition region of the sample; and a computing unit that calculates a local Seebeck coefficient based on the scanning result of the temperature transition region of the sample by the scanning probe microscope. The sample holder comprises a thermally conductive support holding at least a part of each of the heating region and the cooling region, a heating device for heating the support holding the heating region, and the cooling region. and a cooling device that cools the support that holds the arithmetic unit is formed in the temperature transition region between the heating region side and the cooling region side by the heating device and the cooling device The direction of the temperature gradient and the temperature gradient are obtained, the thermoelectromotive voltage distribution is obtained based on the scanning result of the temperature transition region of the sample by the scanning probe microscope, and the temperature transition region is divided into certain sections. Then, from the thermoelectromotive voltage distribution, the average value of the thermoelectromotive voltages in each of the sections is calculated, and from the average value of the thermoelectromotive voltages between the adjacent sections with respect to the direction of the temperature gradient, A voltage gradient is calculated, and a local Seebeck coefficient is calculated based on the temperature gradient and the voltage gradient between the adjacent compartments .

Further, in the method for calculating the Seebeck coefficient according to the present invention, a sample having a substance to be measured which is a scanning target of a scanning probe microscope, is a heating region, a cooling region, and arranged between the heating region and the cooling region. a temperature transition region where the substance to be measured is exposed corresponding to at least the scanning range of the scanning probe microscope; and the sample is held against the scanning probe microscope and the temperature transition region of the sample is and a computing unit that calculates a local Seebeck coefficient based on the result of scanning the temperature transition region of the sample by the scanning probe microscope, wherein the sample holder is A thermally conductive support holding at least a part of each of the heating region and the cooling region, a heating device heating the support holding the heating region, and the support holding the cooling region. a cooling device for cooling; and forming a temperature gradient in the temperature transition region between the heating region side and the cooling region side by the heating device and the cooling device. obtaining the direction of the temperature gradient and the temperature gradient; obtaining a thermoelectromotive voltage distribution based on the scanning result of the temperature transition region of the sample by the scanning probe microscope; and the temperature transition region. is divided into certain sections, calculating the average value of the thermoelectromotive voltage in each section from the thermoelectric voltage distribution; and and calculating a local Seebeck coefficient based on the temperature gradient and the voltage gradient between the adjacent compartments.

Further, the Seebeck coefficient calculation method according to the present invention includes the steps of: preparing the temperature gradient forming device; forming a gradient, obtaining the direction of the temperature gradient and the temperature gradient, and obtaining a thermoelectromotive voltage distribution based on the scanning result of the temperature transition region of the sample by the scanning probe microscope. a step of dividing the temperature transition region into certain sections and calculating an average value of the thermoelectromotive voltage in each section from the thermoelectric voltage distribution; calculating a voltage gradient between the adjacent sections from the average electromotive voltage; and calculating a local Seebeck coefficient based on the temperature gradient and the voltage gradient between the adjacent sections.

In the temperature gradient forming device and Seebeck coefficient calculation method according to the present invention, it is possible to obtain the local thermal properties of the object to be measured.

Schematic explanatory drawing which shows one Embodiment of the sample holder for scanning probe microscopes. Sectional drawing which follows the II-II line of FIG. FIG. 3 is an explanatory diagram of a sample to be scanned by a scanning probe microscope; FIG. 2 is an explanatory diagram of a frequency detection Kelvin probe atomic force microscope, which is an example of a scanning probe microscope. 4 is a flowchart for explaining thermoelectromotive voltage distribution derivation processing; 4 is a flowchart for explaining local Seebeck coefficient derivation processing when the temperature gradient is uniform; 4 is a flowchart for explaining local Seebeck coefficient derivation processing when the temperature gradient is non-uniform; Schematic explanatory drawing which shows the 1st modification of the sample holder for scanning probe microscopes. Schematic explanatory drawing which shows the 2nd modification of the sample holder for scanning probe microscopes. FIG. 10 is a cross-sectional view taken along line XX of FIG. 9; FIG. 11 is a schematic explanatory diagram showing a third modification of the sample holder for scanning probe microscope; Sectional drawing which follows the XII-XII line of FIG.

An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic explanatory diagram showing one embodiment of a sample holder for a scanning probe microscope.

FIG. 2 is a cross-sectional view taken along line II--II of FIG.

A scanning probe microscope sample holder 1 (hereinafter simply referred to as “holder 1 ”) mainly includes a support 2 , a base 3 , a heating device 4 and a cooling device 5 .

The support 2 holds a sample 20 to be scanned (measured) by the scanning probe microscope. The support 2 ensures adhesion and thermal conductivity with the sample 20 for heating of the sample 20 from the heating device 4 and heat transfer accompanying heat absorption from the sample 20 to the cooling device 5, and also has sufficient heat capacity. It has a structure with The support 2 is made of a material having thermal conductivity, and is mainly made of a metal such as copper or stainless steel, and is composed of a material combined with aluminum foil, indium foil, or the like. As shown in FIG. 2, the support 2 holds the sample 20 vertically and horizontally from one side and the opposite side of the sample 20, and the central portion 20a (measurement in FIG. 3) of the sample 20 to be scanned. Support so that the possible area 28) is exposed. In addition to fixing and supporting the sample 20 , the support 2 has a role of equalizing the temperature of the sample area fixed to each support 2 . The support 2 has a heating-side support 2a and a cooling-side support 2b. The heating-side support 2a holds the heating region 25 (described later) side of the sample 20 . The cooling-side support 2b supports the cooling region 26 (described later) side of the sample 20 .

The base 3 is a base member for the entire holder 1, and supports the heating device 4, the high thermal conductivity plate 6, the heat insulating plate 7, and the support 2, which are sequentially stacked from the bottom in the drawing. The base 3 is made of a heat-insulating material such as a ceramic typified by zirconia.

The heating device 4 is, for example, a ceramic heater or a Peltier element, and heats the heating-side support 2a. The heating device 4 is arranged between the base 3 and the support 2 and is shaped like a plate having an outer shape similar to that of the base 3 . A high thermal conductivity plate 6 and a heat insulating plate 7 are arranged on the heating device 4 .

The high thermal conductivity plate 6 is a plate material made of a material having high thermal conductivity such as metal represented by copper or silicon. The high thermal conductivity plate 6 is arranged directly below the support 2a that fixes the heating region 25 of the sample 20. As shown in FIG. Thereby, the heating device 4 is thermally connected to the heating-side support 2 a and the heating region 25 of the sample 20 via the high thermal conductivity plate 6 . The heat insulating plate 7 is a plate material made of a heat insulating material such as fluoride crystal such as magnesium fluoride, glass, or ceramic represented by zirconia. The heat insulating plate 7 is arranged directly below the cooling-side support 2b that holds the cooling region 26 side of the sample 20 . As a result, the heating device 4 is thermally connected to the heating region 25 of the sample 20 via the heating-side support 2a and heats the heating region 25, while being thermally isolated from the support 2b by the insulating plate 7. and does not heat the cooling region 26 .

The cooling device 5 is, for example, a cryostat containing liquid nitrogen, and cools the cooling-side support 2b. The cooling device 5 has a connection member 8 such as a copper ribbon, which has high thermal conductivity and excellent flexibility. The connection member 8 is fixed to the cooling-side support 2 b and the fastener 9 , thereby thermally connecting the cooling-side support 2 b and the cooling device 5 . As a result, the cooling device 5 is thermally connected to the cooling region 26 of the sample 20 via the cooling-side support 2b and cools the cooling region 26, while the heat insulating plate 7 thermally isolates the cooling region 26 from other than the support 2b. It is shut off and does not cool the heating area 25 .

Heating device 4 and cooling device 5 form a temperature gradient in temperature transition region 27 (described below) between heating region 25 and cooling region 26 of sample 20 . That is, on the surface (horizontal surface) of the sample 20 fixed by the support 2, there are a heating region 25 heated by the heating device 4, a cooling region 26 cooled by the cooling device 5, and the heating region 25 and the cooling region A temperature transition region 27 sandwiched between 26 is formed. Here, in order to secure the sensitivity required for the Seebeck coefficient measurement, it is preferable to set the temperature difference in the transition region to 200 degrees or more. Therefore, it is preferable that the heating device 4 has a performance capable of heating in the range of room temperature to 200° C. or higher, for example. As the cooling device 5, it is preferable to apply one having a performance capable of cooling, for example, in the range of −150° C. or below to room temperature. Thereby, a large temperature difference of 200 degrees or more can be realized in the temperature transition region 27 of the sample 20 between the heating region 25 and the cooling region 26 .

Next, an example of the sample 20 and a scanning probe microscope will be described.

FIG. 3 is an explanatory diagram of the sample 20 to be scanned by the scanning probe microscope.

A sample 20 has a substrate 21 , a substance 22 to be measured, and a highly thermal conductive metal thin film 23 . Substrate 21 is a base material for forming measurement substance 22 . The measurement substance 22 is formed on one surface of the substrate 21 and is a thermoelectric material whose Seebeck coefficient is to be calculated. The highly thermally conductive metal thin film 23 (highly thermally conductive film) is gold, for example, and is formed on the surface of the measurement substance 22 opposite to the surface facing the substrate 21 . The highly thermally conductive metal thin films 23 are formed on one side of the substance to be measured 22 and on the other side opposite to this one side with a certain interval therebetween. Thereby, the highly thermal conductive metal thin film 23 contributes to the formation of the heating region 25 , the cooling region 26 and the temperature transition region 27 .

Generally, the scannable range of a scanning probe microscope is as narrow as 100 μm or less per side. The scanning probe microscope in this embodiment must measure the thermoelectromotive voltage distribution associated with the Seebeck effect within this measurement range with sufficient sensitivity. Therefore, it is necessary to give a uniform and large temperature gradient to the measurement material 22 within a scanning width of the scanning probe microscope or within a slightly wider distance.

The high heat conductive metal thin film 23 has the role of equalizing the temperature of the measurement substance 22 immediately below the area covered with the high heat conductive metal thin film 23 . Therefore, the heating region 25 is formed in the region on the measurement substance 22 held by the heating-side support 2a and covered with the highly thermally conductive metal thin film 23. As shown in FIG. A cooling region 26 is formed in a region on the measurement substance 22 that is held by the cooling-side support 2b and covered with the high heat-conducting metal thin film 23. As shown in FIG.

A temperature transition region 27 is formed in a region of the sample 20 other than the heating region 25 and the cooling region 26 where the substance 22 to be measured is exposed without being covered with the high thermal conductivity metal thin film 23 . Also, a measurable region 28 by the scanning probe microscope is the surface of the measurement material 22 that is exposed without being covered with the high thermal conductive metal thin film 23 . This measurable region 28 is also exposed from the support 2 . Since the temperature transition area 27 is not covered with the high thermal conductivity metal thin film 23, a temperature gradient is generated only in this temperature transition area 27. FIG. Limiting the temperature transition region 27 to a narrow range about the scannable range is important in giving a large temperature difference to the measurement material 22 at a short distance, that is, giving a large temperature gradient.

FIG. 4 is an explanatory diagram of a frequency detection Kelvin probe atomic force microscope 30, which is an example of a scanning probe microscope.

A frequency detection type Kelvin probe atomic force microscope 30 (hereinafter simply referred to as "FM-KFM (Frequency-Modulation Kelvin-probe force Microscopy) 30") is an example of a Kelvin probe atomic force microscope, as shown in FIG. has a known device configuration. The FM-KFM 30 measures the shape of the sample 20 with the conductive cantilever 31, applies an alternating voltage between the cantilever 31 and the sample 20, and detects the electrostatic force acting between the probe 32 and the sample 20. Thus, the potential of the surface (measurable region 28) of the sample 20 is measured. The holder 1 is placed on the scanner 34 mounted on the base 33 of the FM-KFM 30 while holding the sample 20 thereon. When measuring with the FM-KFM30, the scan is performed in a vacuum of, for example, 10 ⁻⁴ Pa, with cooling at a fairly low temperature, such as with liquid nitrogen to provide a temperature gradient.

The base 33 is a structurally fixed, non-moving part that forms the foundation of the FM-KFM 30 as a whole. A scanner 34 is mounted on the base 33 and is an actuator for scanning. A sample stage (not shown) is installed on the scanner 34, and the holder 1 is installed on this sample stage. Although FIG. 4 shows an example having a scanner 34 that moves the sample 20 during scanning, the sample 20 may be kept stationary during scanning and the cantilever 31 may be driven by the scanner. 1, 2, and FIGS. 8 to 12, which will be described later, and the heating and cooling device 210 are installed on the FM-KFM 30, not on the scanner 34 (sample stage) described above. It is arranged on a base 33 which is a stationary part.

Next, a method for calculating the Seebeck coefficient will be described. The Seebeck coefficient is calculated by performing thermoelectromotive voltage distribution derivation processing and local Seebeck coefficient derivation processing based on scanning results using FM-KFM30. Arithmetic processing included in the thermoelectromotive voltage distribution derivation processing and the local Seebeck coefficient derivation processing described in FIGS. 5 to 7 can be realized, for example, by executing a program capable of executing these computational processing on a computer.

FIG. 5 is a flowchart for explaining the thermoelectromotive voltage distribution deriving process.

In step S1, the surface potential distribution A (surface potential distribution during temperature gradient) of the measurement substance 22 (sample 20) is obtained while a temperature gradient is formed in the measurement substance 22 (sample 20). Specifically, the heating device 4 and the cooling device 5 of the holder 1 (FM-KFM30) conduct heat transfer with the sample 20 via the support 2, thereby creating a temperature gradient in the measurable region 28 of the sample 20. Form. At this time, the temperature difference between the heating area 25 and the cooling area 26 formed on the sample 20 is set to 100 degrees or more, for example. After the temperature gradient is formed in this manner, the surface potential distribution is acquired by the FM-KFM 30 in the measurable region 28 of the sample 20. FIG.

In step S2, the surface potential distribution of the measurement substance 22 (surface potential distribution at uniform temperature) is obtained while the temperature of the measurement substance 22 is made uniform. Specifically, without operating the heating device 4 and the cooling device 5 of the FM-KFM 30, the surface potential distribution is acquired by the FM-KFM 30 in the measurable region 28 of the measurement substance 22 in a state where there is no temperature gradient.

In step S3, based on the surface potential distribution A when the temperature gradient is formed and the surface potential distribution B when the temperature is uniform obtained in step S1, the potential change due to the presence or absence of the temperature gradient formation of the measurement substance 22 is obtained. Obtain the voltage distribution V(x,y). Specifically, from the difference between the surface potential when the temperature gradient is formed and the surface potential when the temperature is uniform at each point in the measurable region 28, the pure potential change caused by the Seebeck effect due to the formation of the temperature gradient is converted into a thermoelectromotive force. Calculate as For example, a 10 μm×10 μm measurable area 28 (scanning range) is defined by 256×256 pixels. The thermoelectromotive voltage distribution V(x, y) is obtained from the value of the thermoelectromotive voltage at each pixel point, or the distribution of the values of the thermoelectromotive voltage averaged over several square pixels. The thermoelectromotive voltage distribution derivation process is completed as described above, and the process proceeds to the local Seebeck coefficient derivation process.

The local Seebeck coefficient derivation process is performed when the direction and magnitude of the temperature gradient formed on the surface of the measurement substance 22 are uniform, and when they are non-uniform (the direction and magnitude of the temperature gradient is not constant). First, the local Seebeck coefficient derivation processing when the direction of the temperature gradient and the temperature gradient are uniform will be described.

FIG. 6 is a flowchart for explaining local Seebeck coefficient derivation processing when the temperature gradient is uniform.

In step S11, the direction of the temperature gradient and the temperature gradient dT formed in step S1 of the thermoelectromotive voltage distribution deriving process are obtained. In this process, the direction of the temperature gradient and the temperature gradient dT are uniform. The temperature gradient formed on the surface of the sample 20 is obtained by obtaining the temperature difference on the high thermal conductive metal thin film 23 with the 26 side. Therefore, it is not necessary to actually measure the temperature distribution in the range scanned by the FM-KFM30. The temperature difference between the supports 2a and 2b and on the high thermal conductive metal thin film 23 can be obtained by fixing two or more temperature sensors such as thermocouples at the corresponding locations and measuring the temperature.

In step S12, the region where the thermoelectromotive voltage distribution V(x, y) derived in step S3 (thermoelectromotive voltage distribution deriving process in FIG. 5) is obtained is divided into constant minute sections. The dimensions of the microcompartments are arbitrary. For example, if the scan range is defined as 256×256 pixels, the microsections are defined by dividing the scan range into a grid such that each microsection has dimensions of 16×16 pixels. obtain.

In step S13, the thermoelectromotive voltage distribution V(x, y) obtained in step S3 is averaged in each minute division to calculate the average value of the thermoelectromotive voltage in each minute division. In step S14, the voltage gradient dV between adjacent micro-sections in the direction of the temperature gradient is calculated from the average thermoelectromotive voltage in each micro-section obtained in step S13. In steps S13 and S14, the temperature gradient direction voltage It may be replaced by a step of calculating the gradient dV.

In step S15, the local Seebeck coefficient S(x', y') is calculated based on the temperature gradient (temperature gradient between adjacent sections) dT obtained in step S11 and the voltage gradient dV obtained in step S14. do. Specifically, the Seebeck coefficient S is defined as S=dV/dT. Based on this, the resulting value of dV/dT between each adjacent partition is obtained as the local Seebeck coefficient S(x',y'). In step S16, the distribution of the local Seebeck coefficients S(x', y') calculated in each minute section is visualized. Thereby, the distribution of the Seebeck coefficient S(x', y') on the measurement substance 22 becomes visually recognizable. This completes the local Seebeck coefficient derivation process when the temperature gradient is uniform.

Next, the direction of the temperature gradient and the processing for deriving the local Seebeck coefficient when the temperature gradient is non-uniform will be described.

FIG. 7 is a flowchart for explaining local Seebeck coefficient derivation processing when the temperature gradient is non-uniform.

In step S21, a temperature distribution T(x, y) is obtained on the surface of the sample 20. FIG. The temperature distribution is obtained, for example, by measuring the surface temperature of the measurement material 22 with a scanning thermal microscope (not shown).

In step S22, the region where the temperature distribution T(x, y) obtained in step S21 is obtained is divided into constant minute sections. The minute division has the same meaning as that described in step S12 (local Seebeck coefficient derivation processing in FIG. 6).

In step S23, the temperature distribution T(x, y) obtained in step S22 is averaged in each minute section to calculate the average temperature in each section. In step S24, the temperature gradient dT between adjacent micro-sections is calculated from the average temperature in each micro-section obtained in step S23. In step S25, the direction in which the magnitude of the temperature gradient dT is maximized (maximum temperature gradient direction) in a plurality of adjacent sections is extracted. Also, the temperature gradient dT' between adjacent sections is extracted with respect to the direction in which this temperature gradient dT is maximized. It should be noted that steps S23 to S25 are performed in each microscopic section, for example, from the values (a, b) obtained by fitting the temperature distribution T with a plane function T(x, y)=ax+by+c, the direction in which the temperature gradient is maximized. and a step of calculating the value dT'.

Note that steps S21 to S25 correspond to the steps of acquiring the direction of the temperature gradient and the temperature gradient.

Steps S26 and S27 are substantially the same as steps S12 and S13 in FIG. 6, so description thereof will be omitted. In step S28, the voltage gradient dV between adjacent sections in the direction of the temperature gradient dT' is calculated from the average value of the thermoelectromotive voltage of each minute section obtained in step S27.

In step S29, the local Seebeck coefficient S(x', y') is calculated based on the temperature gradient dT' and the voltage gradient dV between adjacent sections with respect to the direction of the temperature gradient dT'. The local Seebeck coefficient S(x', y') is calculated in the same manner as in step S15 of FIG. In step S30, the distribution of the local Seebeck coefficients S(x', y') calculated in each minute section is visualized. This completes the local Seebeck coefficient derivation process when the temperature gradient is non-uniform.

Such a holder 1 and FM-KFM 30 having this holder 1 can form a large temperature gradient on the surface of the sample 20 . As a result, the thermoelectromotive voltage distribution can be suitably obtained with the temperature distribution formed on the surface of the sample 20 . Also, a nanoscale local Seebeck coefficient can be derived by a Seebeck coefficient calculation method based on the obtained thermoelectromotive voltage distribution. As a result, for example, the surface potential distribution can be converted into a temperature distribution, and the nanoscale evaluation of the thermoelectric material can be suitably performed. That is, the scanning probe microscope sample holder, the scanning probe microscope, and the Seebeck coefficient calculation method according to the present embodiment can obtain the local thermal physical properties of the object to be measured.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, although an example in which the scanning probe microscope is FM-KFM has been described, other scanning probe microscopes such as atomic force microscope potentiometry (AFMP) may be used. When the scanning probe microscope is an AFMP, the distribution of measured values obtained as a result of scanning with a temperature gradient formed is a thermoelectromotive voltage distribution due to its operating principle. 5 can be omitted, and the local Seebeck coefficient derivation process shown in FIG. 6 or 7 can be executed. Since FM-KFM can perform non-contact scanning, it is almost unnecessary to consider heat inflow and outflow from the probe. Therefore, it is superior to AMPF in measurement.

Moreover, the heating device and cooling device of the holder are not limited to the heating device 4 and the cooling device 5 described above as long as they can heat and cool the sample via the support and form a temperature gradient.

For example, FIG. 8 is a schematic explanatory diagram showing a first modified example of a sample holder for a scanning probe microscope. In FIG. 8, the same reference numerals are given to the components and parts corresponding to those of the holder 1, and redundant explanations are omitted.
The difference between the holder 1a as the first modification and the holder 1 described above is that the heating device 4 is arranged directly below the heating-side support 2a and the high thermal conductivity plate 6 is omitted. The holder 1 a can be made smaller in height than the holder 1 .

Also, FIG. 9 is a schematic explanatory diagram showing a second modification of the sample holder for scanning probe microscope.
10 is a cross-sectional view taken along line XX of FIG. 9. FIG.

A difference of the holder 100 as the second modified example from the holder 1 is that the heating device 4 is a plurality of Peltier elements 104 . The holder 100 mainly has a plurality of supports 102 , a base 103 , a plurality of Peltier elements 104 and a cooling device 105 .

A support 102 holds a sample 20 to be scanned by a scanning probe microscope. A plurality of supporters 102 sandwich the sample 20 vertically and horizontally so as to surround the sample 20 from the periphery of the sample 20, and support the sample 20 so that the central portion 20a of the sample 20 is exposed.

The base 103 is a member that serves as the base of the entire holder 100, and supports the high thermal conductivity plate 106, the Peltier element 104, and the support 102 that are sequentially laminated from below. A high thermal conductivity plate 106 is located on the base 103 and directly below the Peltier element 104 .

The Peltier element 104 is arranged between the high thermal conductivity plate 106 and the support 2 , and is arranged over at least the entire area immediately below the support 102 . That is, the plurality of Peltier elements 104 are arranged so as to surround the periphery of the sample 20 in the same manner as the support 102 . The Peltier element 104 is thermally connected to the sample 20 via the support 102 .

Cooling device 105 is, for example, a cryostat containing liquid nitrogen. The cooling device 105 has a connecting member 108 embedded in the high thermal conductivity plate 106 . Cooling device 105 is thermally connected to sample 20 via connecting member 108 , high thermal conductivity plate 106 , Peltier element 104 , and support 102 . Thereby, the cooling device 105 is thermally connected to the sample 20 via the support 102 .

In the holder 100, the support 102 at a position corresponding to the Peltier element 104 heating the sample 20 (support 102) can serve as a heating-side support. In addition, the supports 102 other than the support 102 functioning as the heating-side support are not heated by the Peltier element 104 . These supports 102 can become cooling-side supports as a result of heat absorption from the cooling device 105 .

Such a holder 100 can individually control the temperature of each Peltier element 104 . Thereby, the holder 100 can switch between heating and cooling as appropriate according to the desired temperature distribution, and can arbitrarily control the direction and position of the temperature gradient.

Further, FIG. 11 is a schematic explanatory diagram showing a third modification of the sample holder for scanning probe microscope.
12 is a cross-sectional view taken along line XII-XII in FIG. 11. FIG.

The holder 200 mainly has a support 202 , a base 203 , a heat insulating plate 207 and a heating/cooling device 210 . Support 202 and base 203 are substantially the same as support 2 and base 3 in FIGS. 1 and 2 and support 102 and base 103 in FIGS.

A heat insulating plate 207 is arranged between the support 202 and the base 203 . The heat insulating plate 207 is a plate made of a heat insulating material such as fluoride crystal such as magnesium fluoride, glass, or ceramic represented by zirconia. The heat insulating plate 207 has the role of reliably generating a temperature gradient in the horizontal direction of the central portion 20a by limiting heat transfer only between the support 202 and the sample 20. FIG. The heat insulating plate 207 is arranged so that the heat is not transmitted to the base 203 and is prevented from escaping outside the holder 200 from the sample stage of the scanning probe microscope or the like.

The heating and cooling device 210 heats the heating-side support as part of the support 202 and cools the cooling-side support as the other part of the support 202 . A plurality of heating/cooling devices 210 are arranged so as to surround the outer periphery of the support 202 . The heating/cooling device 210 consists of a Peltier element or a mechanism combining a cryostat and a heater. The heating and cooling device 210 has a high thermal conductivity connecting member 208, such as a copper ribbon. The connection member 208 thermally connects the support 202 and the heating/cooling device 210 by being sandwiched between the support 202 and the fastener 209 . Since the operation of the heating/cooling device 45 is the same as that of the heating device 4 and the cooling device 5 in FIGS. 1, 2, and 8 to 10, detailed description thereof will be omitted.

Such a holder 200 can appropriately switch between heating and cooling depending on the desired temperature distribution of each heating/cooling device 210, and can arbitrarily control the direction and position of the temperature gradient.

1, 1a, 100, 200 Sample holder for scanning probe microscope (holder)
2, 102, 202 support tool 2a heating side support tool 2b cooling side support tool 3, 103, 203 base 4 heating device 5, 105 cooling device 6, 106 high thermal conductivity plate 7, 207 heat insulating plate 8, 108, 208 connecting member 9 , 209 fastener 20 sample 22 measurement substance 25 heating region 26 cooling region 27 temperature transition region 28 measurable region 30 frequency detection Kelvin probe atomic force microscope 45 heating and cooling device 104 Peltier element 210 heating and cooling device

Claims (7)

A sample having a substance to be measured to be scanned by a scanning probe microscope, comprising: a heating region; a cooling region; and a temperature transition region where the measurement substance is exposed;
a sample holder that holds the sample against the scanning probe microscope and locally creates a temperature gradient in a temperature transition region of the sample;
a computing unit that calculates a local Seebeck coefficient based on the scanning result of the scanning probe microscope of the temperature transition region of the sample,
The sample holder is
a thermally conductive support that holds at least a portion of each of the heating region and the cooling region;
a heating device that heats the support that holds the heating region;
a cooling device that cools the support that holds the cooling area;
The calculation unit is
Obtaining the direction of the temperature gradient and the temperature gradient formed in the temperature transition region between the heating region side and the cooling region side by the heating device and the cooling device;
Acquiring a thermoelectromotive voltage distribution based on a scanning result of the temperature transition region of the sample by the scanning probe microscope,
dividing the temperature transition region into certain sections, and calculating an average value of the thermoelectromotive voltage in each section from the thermoelectromotive voltage distribution;
calculating the voltage gradient between the adjacent sections from the average value of the thermoelectromotive voltages between the adjacent sections with respect to the direction of the temperature gradient;
A temperature gradient forming device for calculating a local Seebeck coefficient based on the temperature gradient and the voltage gradient between the adjacent compartments . The sample is
a substrate;
the measurement substance formed on one surface of the substrate;
a high thermal conductivity film formed on the surface of the measurement substance opposite to the surface facing the substrate,
The heating region and the cooling region are regions on the measurement substance covered with the high thermal conductivity film,
The temperature transition region is a region other than the heating region and the cooling region,
2. The temperature gradient forming device according to claim 1, wherein said high heat conductive film uniformizes the temperatures of said heating region and said cooling region respectively, thereby forming a temperature gradient only in said temperature transition region. The support is connected to the heating device and the cooling device,
3. The temperature gradient forming device according to claim 1, wherein the region of the sample held by the support is switchable between the heating region and the cooling region. 4. The temperature gradient forming apparatus according to claim 3, wherein said support exposes at least said temperature transition region and holds a peripheral edge of said sample. A sample having a substance to be measured to be scanned by a scanning probe microscope, comprising a heating region, a cooling region, and a region disposed between the heating region and the cooling region corresponding to at least a scanning range of the scanning probe microscope and a temperature transition region in which the substance to be measured is exposed, and a sample holder that holds the sample against the scanning probe microscope and locally forms a temperature gradient in the temperature transition region of the sample. and a computing unit that calculates a local Seebeck coefficient based on the result of scanning the temperature transition region of the sample by the scanning probe microscope, wherein the sample holder defines at least part of the heating region and the cooling region. A temperature gradient forming device comprising: a thermally conductive support holding each; a heating device for heating the support holding the heating region; and a cooling device for cooling the support holding the cooling region. a step of preparing
forming a temperature gradient in the temperature transition region between the heating region side and the cooling region side by the heating device and the cooling device;
obtaining the direction of the temperature gradient and the temperature gradient;
obtaining a thermoelectromotive voltage distribution based on a scanning result of the temperature transition region of the sample by the scanning probe microscope;
a step of dividing the temperature transition region into certain sections and calculating an average value of the thermoelectromotive voltage in each section from the thermoelectromotive voltage distribution;
calculating a voltage gradient between the adjacent sections from the average value of the thermoelectromotive voltages between the adjacent sections with respect to the direction of the temperature gradient;
and calculating a local Seebeck coefficient based on the temperature gradient and the voltage gradient between the adjacent sections. Obtaining the direction of the temperature gradient and the temperature gradient comprises:
obtaining a temperature distribution of the temperature transition region of the specimen;
calculating an average value of the temperature in the compartment from the temperature distribution;
calculating a temperature gradient of the adjacent compartments from the average temperature between the adjacent compartments;
a maximum temperature gradient direction in which the temperature gradient is maximized between a plurality of the adjacent compartments; and extracting a temperature gradient with respect to the maximum temperature gradient direction;
The step of calculating the voltage gradient between the adjacent compartments includes calculating the voltage gradient between the adjacent compartments with the maximum temperature gradient direction as the direction of the temperature gradient,
6. The Seebeck according to claim 5, wherein calculating the local Seebeck coefficient comprises calculating the local Seebeck coefficient based on the temperature gradient and the voltage gradient between the adjacent sections with respect to the maximum temperature gradient direction. Coefficient calculation method. The scanning probe microscope is a Kelvin probe atomic force microscope,
The step of obtaining the thermoelectromotive voltage distribution includes:
a step of forming a temperature gradient with the heating device and the cooling device, and obtaining a temperature gradient surface potential distribution with the scanning probe microscope in a temperature transition region of the sample;
obtaining a uniform temperature surface potential distribution in the temperature transition region with the scanning probe microscope in a state where the temperature of the temperature transition region is made uniform;
obtaining a thermoelectromotive voltage distribution by obtaining a potential change due to heat in the temperature transition region based on the surface potential distribution at temperature gradient and the surface potential distribution at uniform temperature. 6. The method for calculating the Seebeck coefficient according to 6 above.

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