KR101571139B1 - Method and apparatus for calculating the electrical characteristics of amorphous semiconductor thin-film transistor - Google Patents

Abstract

The present invention relates to a method and an apparatus for calculating an electrical characteristic of an amorphous semiconductor TFT, and a method of calculating an electrical characteristic according to the present invention is a method for calculating an electrical characteristic of an amorphous semiconductor TFT by irradiating light to an amorphous semiconductor TFT, The electric capacity of the amorphous semiconductor TFT is computed and modeled as a function of the CV and the state density is calculated by combining the measured light response characteristics and the modeled function to provide the electrical characteristics of the amorphous semiconductor TFT .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for calculating an electrical characteristic of an amorphous semiconductor TFT,

The present invention relates to a method and an apparatus for calculating the electrical characteristics of an amorphous semiconductor TFT. More particularly, the present invention relates to a method and an apparatus for calculating a model parameter that can be utilized in a design simulation for an amorphous semiconductor TFT, And a method for providing an environment in which a simulation can be performed.

Many materials, such as metals and semiconductors, are determined by arranging atoms regularly. The crystal size ranges from 0.1 μm to a large single crystal with a diameter of 0.1 m or more. Non-crystalline or amorphous refers to a state of a solid such that such a long periodic atomic arrangement is broken. Solids with a three-dimensional periodicity in an atomic arrangement are called crystals. A solid that does not have this periodicity is called an amorphous material. The amorphous material is very similar in atomic arrangement to the crystal in the short range, but since there is no long - range order, the physical constant such as melting point is not precisely determined.

A typical example of an amorphous material that has long been known is oxide glass. The glass is not crystallized from the molten state, but is brought to the room temperature as solidified disordered structure. The term amorphous refers to a solid concept that does not have a crystal structure in its expanded concept. When cooled from the melt, oxides such as SiO ₂ and B ₂ O ₃ are difficult to crystallize and become amorphous. However, metals and semiconductors tend to crystallize and amorphous can not be obtained by ordinary methods. Semiconductors using such amorphous materials are amorphous semiconductors.

A method for realizing an amorphous state in such metals and semiconductors has been invented and materials obtained therefrom have exhibited new properties. A representative example of such an amorphous semiconductor is amorphous silicon. Amorphous silicon has a band structure that is not clearly defined and has a state in a bandgap. As a semiconductor, its performance is lower than that of a single crystal. Hydrogenated amorphous silicon, in which a material ratio is low and an unbound state is saturated with hydrogen, Since it is possible to control, it is possible to make pn junction diode or transistor like single crystal semiconductor. In addition, since it can be deposited in a large area at a low temperature, it can be used as a thin film transistor or a photoconductor for electrophotography, and is used in solar cells because of its large absorption coefficient. In particular, in recent years, industrial value is increasing in flexible and trasparent display device applications.

Specifically, in the case of an amorphous semiconductor, the position of the lowest point of the conduction band is located in the metal cation ns orbital, so that mobility close to the band mobility can be obtained irrespective of crystal directions Point and the density of state (DOS) values are very low compared to monocrystalline semiconductors.

In the case of monocrystalline semiconductors, many studies have been carried out for predicting and calculating their electrical characteristics, and models that can be applied to commercial tools for circuit design such as SPICE have been proposed. On the other hand, in the case of amorphous semiconductors, there are difficulties in presenting models that accurately predict the electrical characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and it is an object of the present invention to overcome the limit of difficulty in accurately calculating the electrical characteristics of an amorphous semiconductor TFT and to solve the problem that conventional techniques can not provide model parameters that can be utilized in simulation for an amorphous semiconductor TFT . Furthermore, the present invention aims at solving the problem that correct simulation for an amorphous semiconductor TFT can not be performed due to no accurate model parameter being provided.

According to an aspect of the present invention, there is provided a method of calculating an electrical characteristic of an amorphous semiconductor TFT according to the present invention, comprising the steps of: irradiating the TFT with light to measure a light response characteristic of the C-V; Calculating electric capacities of the case where the light is not irradiated and the case where the light is irradiated, and modeling the electric capacity as a function of the C-V; And calculating the state density by combining the measured light response characteristic and the modeled function.

According to an aspect of the present invention, there is provided a method of calculating an electrical characteristic of an amorphous semiconductor TFT, comprising: measuring and inputting a channel mobility of the TFT; Modeling channel mobility from the state density using a predetermined parameter; And determining the final state density by matching the modeled channel mobility with the measured channel mobility.

According to an aspect of the present invention, there is provided a method of calculating an electrical characteristic of an amorphous semiconductor TFT, comprising: measuring and inputting an I-V characteristic of the TFT; Modeling the I-V characteristic from the state density using a predetermined parameter; And determining the final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic.

A computer-readable recording medium on which a program for causing a computer to execute a method for calculating electrical characteristics of the above-described amorphous semiconductor TFT is provided.

According to an aspect of the present invention, there is provided an apparatus for calculating an electrical characteristic of an amorphous semiconductor TFT, comprising: an input unit for irradiating light to the TFT to measure a light response characteristic of the C-V; A modeling unit for calculating the capacitance of each of the case where the light is not irradiated and the case where the light is irradiated, and modeling the capacitance as a function of the C-V; And a calculator that receives the measured light response characteristics and calculates a state density in combination with the modeled function.

The present invention emulates the state density of amorphous semiconductor TFTs experimentally to accurately model the electrical characteristics of amorphous semiconductor TFTs and provides accurate model parameters that can be used in simulations for amorphous semiconductor TFTs to optimize fabrication process conditions, Optimization of the device structure through performance prediction, prediction of circuit characteristics, and simulation environment for this can be provided.

Before describing embodiments of the present invention, embodiments of the present invention are illustrated and described with reference to an amorphous oxide semiconductor thin-film transistor (TFT), but this is merely an example for convenience of description, It is to be noted that the present invention can be applied throughout the amorphous semiconductor rather than the crystalline semiconductor. Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings.

1 is a flow chart showing a method of calculating an electrical characteristic of an amorphous semiconductor TFT according to an embodiment of the present invention, including the following steps.

In step 110, the amorphous semiconductor TFT is irradiated with light, and the light response characteristic of the C-V is measured and input. Specifically, the light-responsive characteristic of the CV is measured by irradiating a photon having an energy smaller than the energy band gap of the amorphous semiconductor to the amorphous semiconductor TFT and comparing the photoresponse characteristic of the irradiated CV As shown in FIG. Here, the capacitance-voltage (C-V) characteristic means a characteristic in which capacitance changes in accordance with a change in a voltage applied to a semiconductor TFT.

See FIG. FIG. 2 is a view for explaining a method of extracting a state density using optical charge pumping and CV characteristics in a method of calculating an electric property of an amorphous semiconductor TFT, which illustrates an a-GaInZnO TFT as an amorphous semiconductor have.

2 shows that electrons trapped in a bulk DOS state between (E _C -E _ph ) and Fermi level E _F are excited by conduction band E _C by receiving photon energy by photon irradiation, . In this case, the band-to-band generation inside the amorphous semiconductor can be ignored by irradiating the amorphous semiconductor TFT with a subgap photon having an energy smaller than the energy band gap of the amorphous semiconductor. Therefore, the change in the capacitance when light is not irradiated and the change in capacitance when light is irradiated can be modeled by the change in capacitance due to the total amount N of electrons excited to the conduction band in the bulk state of the energy range.

Referring back to FIG. 1, in step 120, each of the capacitances when the light is not irradiated and when the light is irradiated is calculated and is modeled as a function of CV, that is, a function of the gate-source voltage (V _GS ).

The change in the electrostatic attraction can be expressed by the following equation (1) as a small signal capacitance.

Where C _dark is the capacitance when light is not applied, C _photo is the capacitance when light is examined, C _ox is the gate oxide insulator capacitance, C _B is the capacitance is the capacitance caused by the reaction trapped charge _{(V GS -responsive localized trapped charge)} , C GIZO is light in a fixed V _GS - - free state (dark state) under GIZO active layer (active layer) V _GS in the reaction charge (photo -responsive charges (? Q) and / or electrons (? N), and? V _gs represents the small signal voltage in the CV measurement.

Then, C _GIZO can be summarized by the following equation (2) by the equation (1).

Equation 2 represents V _GS for one voltage. To calculate the V _GS for one voltage, the radius of the optical fiber is denoted by r, the quasi-fermi level is denoted by E _F ( V _GS) LA and converted to the resolution of the V _GS that scans when CV measurement ΔV _GS La when the optical density of the reaction N by the following equation (3) of the electronic density (photo-responsive electron density) n [cm -3] can do.

Equation (3) is obtained by calculating Equation (2) with respect to the volume of the optical fiber, and the state density g (E) is summarized by the following Equation (4)

Finally, the state density is calculated by combining the optical response characteristics measured in steps 130 and 110 of FIG. 1 and the function modeled through step 120. FIG. As shown in the above-described Equations 3 and 4, the photo-responsive energy range of the state density g (E) is V _GS and E _{ph .} And it is necessary to map the energy range using the relationship between V _GS and surface potential φ _s . As shown in FIG. 2, the energy level matching is determined by assuming that two transition points of the CV curve are E _i (midgap) and the conduction band minimum E _C , respectively.

3.2 eV 이고, 최대 optical power P_opt=50 mW).3A is a diagram illustrating a result of measuring the optical response of an actual CV characteristic using photocharge pumping according to an embodiment of the present invention. (Λ = 654 nm, E _ph = 1.90 eV <E _{g , GIZO}

3.2 eV, maximum optical power P _opt = 50 mW).

FIG. 3B is a diagram illustrating the result of extracting the density of states using photocharge pumping and C-V characteristics under the assumption of FIG. 3A. The state density graph is modeled as a combination of an exponential tail state and a Gaussian deep state, and is expressed by the following Equation (5).

The above-described method is based on the assumption that the gate voltage V _GS and the surface potential φ _s are simply proportional to each other and that the energy band bending in the depth direction of the a-GaInZnO channel is not severe It is possible to determine the more accurate and reliable state density considering the nonlinear relation between the gate voltage V _GS and the surface potential φ _s by reflecting the obtained parameters to the additional simulation model. The detailed method for determining the final state density will be described below again.

4 is a flow chart showing a method for determining the final state density in a method of calculating the electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention, which further includes additional steps in steps 110 to 130 described in FIG. 1 do. Hereinafter, only the steps after step 130 will be described for the sake of convenience.

In step 115, the channel mobility of the amorphous semiconductor TFT is measured and input. The channel mobility can be input in step 110 as well as the measurement result.

In step 140, the channel mobility is modeled from the state density using the parameters determined by the state density calculated in step 130. The state density modeling method proposed above with reference to Equations (3) to (5) assumes that the gate voltage V _GS and the surface potential φ _s are simply proportional to each other. However, since it corresponds to a nonlinear function, Modification of the state density model is needed. That is, although the state density value is determined for the state density calculated in step 130, the energy density mapping of the state density corresponds to an incomplete state density due to the uncertainty of the relationship of V _GS -φ _s . Thus, step 140 determines the V _GS -φ _s relationship by varying the modeling parameters, and models the channel mobility based on the determined V _GS -φ _s relationship. A specific method of modeling the channel mobility will be described later with reference to FIG.

In step 150, the final state density is determined by matching the channel mobility modeled in step 140 with the channel mobility measured in step 115. The state density determined through such a matching process is output as the final state density indicating the electrical characteristics of the amorphous semiconductor TFT, since it is a result of accurate energy level mapping of the state density.

Meanwhile, in order to determine the final state density, it is preferable to repeatedly adjust the above-described parameters until the channel mobility modeled in step 140 corresponds to the channel mobility measured in step 115. [ This repetition naturally verifies the correspondence between the modified model and the measurement result, so that accurate simulation results can be obtained even if the determined final state density is utilized in circuit simulation for an amorphous semiconductor TFT. That is, the final state density can be utilized as a reliable model parameter for circuit simulation.

5 is a flow chart illustrating a method for determining a final IV model in a method of calculating an electrical characteristic of an amorphous semiconductor TFT according to another embodiment of the present invention, wherein the steps 110 to 130 described in FIG. . Hereinafter, only the steps after step 130 will be described for the sake of convenience.

In step 117, a correlation (hereinafter referred to as I-V characteristic) between the current and the voltage of the amorphous semiconductor TFT is measured and input. The I-V characteristic can be input in step 110 and the measurement result.

In step 160, the IV characteristic is modeled from the state density using the parameter determined by the state density calculated in step 130. FIG. The state density modeling method proposed in relation to equations (3) to (5) above assumes that the gate voltage V _GS and the surface potential φ _s are simply proportional to each other. However, since they are actually nonlinear functions, It is necessary to revise. Thus, step 160 is by varying the model parameters determining a relationship between V _GS -φ _s, and modeling based on the determined teukseongreul IV V _GS -φ _s relationship. A specific method of modeling the IV characteristic will be described later with reference to FIG.

The final I-V model is determined by matching the I-V characteristic modeled in step 170 to the I-V characteristic measured in step 117. [ The I-V model determined through such a matching process is output as the final I-V model showing the electrical characteristics of the amorphous semiconductor TFT, since the energy level mapping of the state density is made correctly.

Meanwhile, in order to determine the final I-V model, it is desirable to repeatedly adjust the parameters until the I-V characteristic modeled in step 160 matches the I-V characteristic measured in step 117. Since the matching between the modified model and the measurement result is naturally verified through the repetition, accurate simulation results can be obtained even when the determined final I-V model is used for circuit simulation for the amorphous semiconductor TFT.

At this time, one consideration is the effect of the source / drain parasitic resistance R _P , including the contact resistance. Regarding the actual electrical characteristics, an amorphous oxide semiconductor TFT having a low channel resistance due to a high channel mobility μ _CH is more sensitive to the parasitic resistance R _P than a monocrystalline oxide semiconductor TFT. For example, the a-GaInZnO TFT has a much larger influence on the electrical characteristics of the parasitic resistance than the CMOS device, such as contact resistance and source / drain diffusion resistance.

Therefore, in calculating the electrical characteristics of the amorphous semiconductor TFT to which the embodiments of the present invention are applied, it is necessary to fully consider the influence of the parasitic resistance. 6 is a sectional view of an amorphous semiconductor TFT for explaining a method of calculating parasitic resistance in an amorphous semiconductor TFT. The contact resistance is represented by R _C , the source / drain diffusion resistance by R _SP , and the channel resistance by R _CH . These resistors affect the parasitic resistance R _P. Hereinafter, a definite process for calculating the parasitic resistance R _P using these elements as parameters is presented.

Particularly, in the case of a short channel TFT, the influence of parasitic resistance becomes larger. Furthermore, the contact of the TFT is non-linear due to Schottky, and the source / drain diffusion resistance is also closely related to the state density property of the amorphous semiconductor TFT bulk, and the parasitic resistance R _P is the gate- The voltage V _GS , the drain-source voltage V _DS and the channel length L. In order to model the short channel effect and the intrinsic channel of the TFT, a method of simply and accurately extracting R _P (V _GS , V _DS ) is needed.

In the embodiment of the present invention, the parasitic resistance R _P (V _GS ) is calculated from the transfer curve (I _DS -V _GS ) of the TFT, and R _P (V _DS ) is calculated from the transition curve for various V _DS . Assuming that the channel resistance r _CH per unit channel length and the parasitic resistance r _p per unit spreading path (L _SD ) are independent of the two Ls with small differences, the R _T1 and R _T2 can be expressed by the following Equation (6).

Here, since r _CH1 and r _CH2 are the same, R _P (V _GS ) can be extracted as shown in the following Equation (7).

Using the above-described calculation method, it is possible to extract only R _P (V _GS , V _DS ), which means that only two TFTs having different Ls can be used.

7 is a graph showing the result of calculation of parasitic resistance and total resistance using a method of calculating an electric characteristic of an amorphous semiconductor TFT according to another embodiment of the present invention, wherein a-GaInZnO TFT is used as an amorphous semiconductor TFT R _P (V _GS , V _DS ) and R _T (V _GS , V _DS ).

As described above, the method of modeling the I-V characteristic according to the embodiment of the present invention can provide a model that accurately reflects the internal voltage applied to the TFT by calculating the parasitic resistance from the transition curve of the TFT.

Meanwhile, in FIG. 5, the determination of the relation of V _GS -φ _s can be concurrent with the determination of the channel mobility described above with reference to FIG. In other words, both of FIGS. 4 and 5 calculate the state density through step 130, and modify the state density and the IV characteristic through the relation of V _GS -φ _s . Thus, through adjustment of the parameters in FIGS. 4 and 5, the final V _GS -? _S , the final state density and the final IV model can be determined at the same time, and these results are accurate model parameters that can be used in simulations for amorphous semiconductor TFTs . Hereinafter, algorithms for calculating the electrical characteristics of the amorphous semiconductor TFT described above will be described in order using mathematical expressions. The mathematical formulas to be described below are based on the above-described ones, but are arranged in accordance with each process of FIG. 8 for convenience.

8 is a flow chart illustrating a specific method of calculating the electrical characteristics of the amorphous semiconductor TFT. The measured value 810 is input and calculated (820) in accordance with the electrical characteristic calculating method. As a result, the model parameter 830 is outputted FIG. 8, μ _BAND is the conduction band mobility, μ _CH is the intrinsic channel mobility, N _C is the conduction band effective states, E _FO is the equilibrium Fermi level φ _S is the source channel potential, φ _SD is the drain channel potential (drain potential), φ _S is the surface potential, R _P is the source / drain parasitic resistance, φ _SS is the source channel potential, channel potential, and V _DS 'represents the internal voltage of V _DS .

First, in step 810, I-V characteristics, C-V, and Hall effect are measured and input to the TFT under specific process conditions.

In operation 820, the electrical characteristics of the amorphous semiconductor TFT are calculated using the measured values input through operation 810. Specifically, in step 822, the state density is calculated by combining the photocathode pumping described in FIGS. 1 to 3B and the CV characteristics of the amorphous semiconductor TFT. That is, μ _BAND , N _C , and E _FO are obtained from the Hall effect measurement values input through step 810, and the state density is calculated by photocharge pumping and the following equation (8).

The state density is calculated as described above, but the density of state density is not satisfied because of the uncertainty of the relationship between V _GS and φ _s . Furthermore, since the relationship between V _GS and φ _s is a nonlinear function, it is necessary to modify the state density mapped by photo-electric pumping to the energy level mapping.

In step 823, N _TA , kT _TA , N _DA , and kT _DA are used as parameters 827 for the density of states to calculate the relationship between V _GS and φ _s . The relation between V _GS and φ _s is calculated by the following equation (9).

In step 825 V _{GS -} model the channel mobility by using the following equation (10) from the relation φ _s.

In addition, in step 821, the measured channel mobility is input. The measured channel mobility is expressed by the following Equation (11).

Here, the embodiment of the present invention matches the modeled channel mobility with the actually measured channel mobility. That is, by modifying the V _{GS -} φ _s relationship used to model the channel mobility, the channel mobility closest to the measured channel mobility can be modeled. By the way, as can be seen in equation 10, V _{GS -} this in order to calculate the relation φ _s of the parameter of density of states 827 is required. Thus, there is a need for the state density parameters 827 used prior to modeling the channel mobility to be revised to match the measured channel mobility and the modeled channel mobility. Thus, embodiments of the present invention utilize an iteration technique for modifying these parameters 827.

On the other hand, in step 826, the IV characteristic is modeled from the relationship V _{GS -} φ _s . At this time, the parasitic resistance _Rp (V _GS , V _DS ) is calculated in order to accurately reflect the internal voltage applied to the TFT channel in step 824 before modeling the IV characteristic. The parasitic resistance can be calculated by the following equation (12) using the transition curve of the TFT.

The modeling I-V characteristic is compared with the measured value of the I-V characteristic input through step 810 again. That is, the modeling parameters 827 are modified to match the I-V characteristics modeled in step 826 with the I-V characteristics measured in step 810. These parameters are modified through repetition as previously described in the Channel Mobility Matching method.

As a result, the channel mobility calculated from the state density parameters 827 according to this repetition technique is repeated to change the parameters until the measured channel values m _CH (V _GS ) and the modeled IV coincide with corresponding measurement values . If the final state density is determined through this repetition, the instantaneous channel mobility μ _CH (V _GS ) at which the final state density is determined is determined, since the naturally coincidence with the measurement result is verified during the repetition process. The final V _{GS -} φ _s relation, the final IV characteristics, etc. are simultaneously output.

Through the embodiments of the present invention, it becomes possible to model amorphous semiconductor TFTs, which means that it is possible to establish model parameters for circuit simulation.

9 is a diagram showing an apparatus 900 for calculating electrical characteristics of an amorphous semiconductor TFT according to an embodiment of the present invention. The apparatus 900 includes an input section 910, a modeling section 920, a calculating section 930, 940). The present embodiment is implemented as an apparatus corresponding to the method of FIGS. 1, 4, and 5 described above, and only the device characteristics will be described here, and a detailed description of the operation method will be omitted.

The input unit 910 irradiates light to the amorphous semiconductor TFT, measures the light response characteristic of the C-V, and receives the result. In addition, the input unit 910 can measure the channel mobility of the amorphous semiconductor TFT in relation to the channel mobility modeling, receive the result of the measurement, and measure the IV characteristics of the amorphous semiconductor TFT in relation to the IV characteristic modeling. Input can be received. The input unit 910 may physically be an apparatus that receives and measures an object, but may also include various communication means capable of receiving measured results in an electronic form.

The modeling unit 920 calculates each of the capacitances when the light is not irradiated and when the light is irradiated, and models it as a function of the C-V. With respect to the channel mobility, the channel mobility can be modeled from the state density by using the state density parameter, and the I-V characteristic can be modeled from the state density by using the parameter of the state density with respect to the I-V characteristic. As described above, the modeling unit 920 performs the modeling of the CV, the channel mobility and the IV characteristic in the electronic form through various mathematical expressions derived from the physical characteristics of the amorphous semiconductor TFT, a processor or an equivalent operator. It goes without saying that a memory for additional operations can be used to perform these modeling operations.

The calculating unit 930 receives the measured light response characteristics and combines them with a function modeled by the modeling unit 920 to calculate a state density. The calculating unit 930 may also be implemented as a processor of a conventional computer system or a computing unit equivalent thereto.

The decision unit 940 can determine the final state density by matching the modeled channel mobility with the measured channel mobility or determine the final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic. The channel mobility and IV characteristics can all be matched to the measured values by modifying the iterative state density and the modeling results are different depending on the parameters of the state density. And IV characteristics. Therefore, if a parameter having a state density matching the measured value with the modeled value is found, the final state density and the final I-V characteristic can be determined through the determination unit 940 and output as a result value. The determination unit 940 may also be implemented by a processor of a conventional computer system or a computing unit equivalent thereto.

Although the modeling unit 920, the calculating unit 930, and the determining unit 940 described above are conceptually separated from each other due to differences in function, all of the components are implemented as a general-purpose processor for processing electronic data and a storage space .

Meanwhile, the present invention can be embodied in computer readable code on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device and the like, and also a carrier wave (for example, transmission via the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers skilled in the art to which the present invention belongs.

The present invention has been described above with reference to various embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

1 is a flowchart showing a method of calculating an electrical characteristic of an amorphous semiconductor TFT according to an embodiment of the present invention.

FIG. 2 is a view for explaining a method of extracting a state density using photocharge pumping and C-V characteristics in a method of calculating electrical characteristics of an amorphous semiconductor TFT according to an embodiment of the present invention.

FIG. 3A is a diagram illustrating a result of optical response measurement of C-V characteristics using photocharge pumping according to an embodiment of the present invention.

FIG. 3B is a diagram illustrating a result of extracting a state density using photocharge pumping and C-V characteristics according to an embodiment of the present invention.

4 is a flowchart illustrating a method for determining a final state density in a method of calculating the electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention.

5 is a flow chart illustrating a method for determining the final I-V model in a method for calculating the electrical properties of an amorphous semiconductor TFT according to another embodiment of the present invention.

6 is a cross-sectional view of an amorphous semiconductor TFT for explaining a method of calculating a parasitic resistance in an amorphous semiconductor TFT.

7 is a diagram illustrating a result of calculating a parasitic resistance and a total resistance using a method of calculating an electric characteristic of an amorphous semiconductor TFT according to another embodiment of the present invention.

8 is a flowchart illustrating a specific method of calculating the electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention.

9 is a diagram showing an apparatus for calculating electrical characteristics of an amorphous semiconductor TFT according to an embodiment of the present invention.

Claims (11)

A method of calculating electrical characteristics of an amorphous semiconductor TFT, Measuring light response characteristics of the C-V by irradiating the TFT with light; Calculating electric capacities of the case where the light is not irradiated and the case where the light is irradiated, and modeling the electric capacity as a function of the C-V; And And calculating the state density by combining the measured light response characteristic and the modeled function. The method according to claim 1, The step of measuring the light response characteristic of the C- Irradiating the TFT with a photon having energy smaller than an energy band gap of the amorphous semiconductor; And Measuring a change in the light response characteristic of the C-V after irradiation of the photon with respect to the light response characteristic of the C-V before irradiation of the photon. The method according to claim 1, Measuring and inputting a channel mobility of the TFT; Modeling channel mobility from the state density using a predetermined parameter; And And determining the final state density by matching the modeled channel mobility with the measured channel mobility. The method of claim 3, Wherein determining the final state density comprises repeatedly adjusting the parameter until the modeled channel mobility coincides with the measured channel mobility. The method according to claim 1, Measuring and inputting I-V characteristics of the TFT; Modeling the I-V characteristic from the state density using a predetermined parameter; And Determining a final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic. 6. The method of claim 5, Wherein the step of determining the final I-V model repeatedly adjusts the parameter until the modeled I-V characteristic matches the measured I-V characteristic. 6. The method of claim 5, Wherein modeling the I-V characteristic is modeled by reflecting an internal voltage applied to the TFT by calculating a parasitic resistance from a transition curve of the TFT. A computer-readable recording medium storing a program for causing a computer to execute the method according to any one of claims 1 to 7. 1. An apparatus for calculating an electrical characteristic of an amorphous semiconductor TFT, An input unit for receiving the light by irradiating the TFT to measure the light response characteristic of the C-V; A modeling unit for calculating the capacitance of each of the case where the light is not irradiated and the case where the light is irradiated, and modeling the capacitance as a function of the C-V; And And a calculation unit that receives the measured light response characteristics and calculates a state density in combination with the modeled function. 10. The method of claim 9, Wherein the input unit measures and inputs a channel mobility of the TFT, The modeling unit models channel mobility from the state density using a predetermined parameter, And determining a final state density by matching the modeled channel mobility with the measured channel mobility. 10. The method of claim 9, The input unit measures and inputs I-V characteristics of the TFT, The modeling unit models an I-V characteristic from the state density using a predetermined parameter, And determining a final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic.

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