KR20100135049A - Method and apparatus for calculating the electrical characteristics of amorphous semiconductor thin-film transistor - Google Patents

Abstract

PURPOSE: By providing the exact model parameter which a method and apparatus for producing the electrical characteristic of the amorphous semiconductor T F T can be used for the simulation for the amorphous semiconductor TFT. CONSTITUTION: The light is examined in the amorphous semiconductor TFT and the light response characteristics of C-V is measured at(110). The electric capacity of the case of examining the light and the case which does not examine the light is calculated and it is modelled to the function of C-V(120).

Description

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

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

Many materials, such as metals and semiconductors, have atoms arranged regularly to form crystals. The grain size varies from microcrystals of about 0.1 μm to large single crystals having a diameter of 0.1 m or more, but amorphous or amorphous refers to a state in which such a long-range periodic atomic array is broken. Solids with three-dimensional periodicity in atomic arrangement are called crystalline. Solids without such periodicity are called amorphous materials. In amorphous materials, the arrangement of atoms at short distances is very similar to that of crystals, but due to the lack of long-range order, physical properties such as melting point are not accurately determined.

A representative material known for a long time as an amorphous material is oxide glass. The glass brought the solidified disordered structure to room temperature without crystallization from the molten state. Amorphous is an enlarged concept here that refers to a solid that does not have a crystal structure. When cooled from the melt, oxides such as SiO ₂ and B ₂ O ₃ are difficult to crystallize into an amorphous state, but metals and semiconductors are easy to crystallize, and amorphous is not obtained by the usual method. A semiconductor using such an amorphous material is an amorphous semiconductor.

In such metals and semiconductors, a method for realizing an amorphous state has been invented and the material obtained therefrom exhibits new physical properties. A representative example of such an amorphous semiconductor is amorphous silicon. Amorphous silicon is a semiconductor, which has a definite band structure and a state within a bandgap, which is a semiconductor, which is inferior in performance to a single crystal. Since control is possible, a pn junction diode or a transistor can be made like a single crystal semiconductor. In addition, it can be used as a thin film transistor or an electrophotographic photosensitive member because it can be deposited in a large area at low temperature, and is used in solar cells because of its large light absorption coefficient. In particular, in recent years, industrial value is increasing in the field of flexible and trasparent display device applications.

Specifically, in the case of the amorphous semiconductor, the lowest point of the conduction band is located in the metal cation ns orbital, so that mobility close to band mobility can be obtained regardless of the crystal directions. The very low point and density of state (DOS) values result in significantly better mobility than single crystalline semiconductors.

In general, in the case of a monocrystalline semiconductor, many studies have been conducted to predict and calculate its 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.

The technical problem to be solved by the present invention is to overcome the limitation that it is difficult to accurately calculate the electrical characteristics of the amorphous semiconductor TFT, and solve the problem that the conventional techniques could not provide a model parameter that can be utilized in the simulation for the amorphous semiconductor TFT It is. Furthermore, the present invention seeks to solve the problem of not being able to perform an accurate simulation on an amorphous semiconductor TFT because an accurate model parameter is not provided.

In order to solve the above technical problem, the method for calculating the electrical characteristics of the amorphous semiconductor TFT according to the present invention comprises the steps of receiving the light by measuring the optical response characteristics of the C-V by irradiating light to the TFT; Modeling each of the capacitances of the non-irradiated light and the irradiated light as a function of C-V; And combining the measured optical response characteristics with the modeled function to calculate a state density.

In order to solve the above technical problem, the method for calculating the electrical characteristics of the amorphous semiconductor TFT according to the present invention comprises the steps of measuring and receiving the channel mobility of the TFT; Modeling 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.

In order to solve the above technical problem, a method for calculating the electrical characteristics of an amorphous semiconductor TFT according to the present invention comprises the steps of measuring and receiving the I-V characteristics of the TFT; Modeling I-V characteristics from the state density using predetermined parameters; And determining a final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic.

Further, the following provides a computer readable recording medium having recorded thereon a program for causing a computer to execute the method for calculating the electrical characteristics of the amorphous semiconductor TFT described above.

In order to solve the above technical problem, an apparatus for calculating the electrical characteristics of the amorphous semiconductor TFT according to the present invention comprises: an input unit for receiving the TFT by measuring light response characteristics of the C-V by irradiation with light; A modeling unit for calculating each of the capacitances when no light is irradiated with light and modeling the capacitance as a function of C-V; And a calculator configured to receive the measured optical response characteristic and calculate a state density by combining with the modeled function.

The present invention experimentally calculates the state density of an amorphous semiconductor TFT to accurately model the electrical characteristics of the amorphous semiconductor TFT, and provides accurate model parameters that can be utilized for simulation for the amorphous semiconductor TFT, thereby optimizing the fabrication process conditions, device It can provide optimization of device structure through performance prediction, prediction of circuit characteristics and simulation environment for it.

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

1 is a flowchart illustrating a method of calculating electrical characteristics of an amorphous semiconductor TFT according to an embodiment of the present invention, and includes the following steps.

In step 110, the amorphous semiconductor TFT is irradiated with light to measure and receive an optical response characteristic of the C-V. Specifically, the optical response characteristic measurement of CV firstly irradiates the amorphous semiconductor TFT with a photon having an energy smaller than the energy bandgap of the amorphous semiconductor, and the optical response characteristic of the CV after irradiation as compared to before the photon irradiation. By measuring the change in. Here, the capacitance-voltage (C-V) characteristic means a characteristic in which the capacitance changes with the change of the voltage applied to the semiconductor TFT.

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

FIG. 2 shows electrons trapped in the bulk DOS state between (E _C -E _ph ) and the Fermi level E _F receiving photon energy by photon irradiation and excitation to the conduction band E _C. Shows the status. 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 interval of the amorphous semiconductor. Therefore, the change in capacitance when no light is irradiated and the capacitance when light is irradiated may be modeled as a change in capacitance due to the total amount N of electrons excited in the conduction band in the bulk state of the corresponding energy range.

Returning to FIG. 1, in step 120, each of the capacitances when no light is irradiated and when light is irradiated is calculated and modeled as a function of CV, that is, a function of gate-source voltage V _GS .

When the change in the electrostatic flux is developed into a small signal capacitance, it can be expressed as Equation 1 below.

Where C _dark is the capacitance when no light is irradiated, C _photo is the capacitance when light is irradiated, C _ox is the gate oxide insulator capacitance, and C _B is the light 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 capacitance due to -responsive charges (ΔQ) and / or electrons (ΔN), where ΔV _gs represents the small signal voltage in the CV measurement.

Then, C _GIZO may be summarized as Equation 2 by Equation 1.

Equation 2 represents V _GS for one voltage, and in order to calculate it for the entire interval, the radius of the optical fiber is r, and the quasi-fermi level is 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 calculates Equation 2 with respect to the volume of the optical fiber, and by the above Equation 3, the state density g (E) is summarized as in Equation 4 below.

Finally, the density of states is calculated by combining the optical response characteristics measured in step 130 in step 130 of FIG. 1 with the modeled function in step 120. As in Equation 3 and Equation 4 described above, the photo-responsive energy range of the state density g (E) is V _GS and E _{ph .} It can be adjusted according to the value. Specifically, the corresponding energy range should be mapped using the relationship between V _GS and the surface potential φ _s . As shown in FIG. 2, energy level matching is determined assuming two transition points of the CV curve as E _i (midgap) and conduction band minimum E _C , respectively.

3.2 eV 이고, 최대 optical power P_opt=50 mW).FIG. 3A illustrates an optical response measurement result of actual CV characteristics using optical charge pumping according to an embodiment of the present invention. FIG. 3A is a sub-interval photon having an energy of 1.9 eV as an optical source for light irradiation. Assume that (λ = 654 nm, E _ph = 1.90 eV <E _{g , GIZO}

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

FIG. 3B is a diagram illustrating a result of extracting a state density using optical charge pumping and C-V characteristics under the assumption of FIG. 3A. The state density graph is modeled as a combination of exponential tail state and Gaussian deep state, and is expressed as in Equation 5 below.

The proposed methods through Equations 3 to 5 above are made under the assumption that the gate voltage V _GS and the interfacial potential φ _s are simply proportional to each other and that the energy band bending in the a-GaInZnO channel depth direction is not severe. It is possible to determine the more accurate and reliable state density by considering the nonlinear relation of gate voltage V _GS and interfacial potential φ _s by reflecting the parameters obtained here in additional simulation model. The detailed method of determining the final state density is described again below.

FIG. 4 is a flowchart illustrating a method of determining a final state density in a method of calculating electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention, further including steps 110 to 130 described in FIG. 1. do. For convenience, only the process after step 130 will be described for convenience.

In step 115, the channel mobility of the amorphous semiconductor TFT is measured and received. The channel mobility may be inputted with the measurement result in step 110.

In step 140, the channel mobility is modeled from the state density using the parameter determined by the state density calculated in step 130. As described above with respect to Equations 3 to 5, the proposed state density modeling method assumes that the gate voltage V _GS and the interfacial potential φ _s are simply proportional to each other. Modification of the state density model is necessary. That is, the state density calculated through step 130 corresponds to the state density whose state density value is determined, but the energy level mapping of the state density is not complete due to the uncertainty of the V _GS -φ _s relationship. Thus, step 140 is by varying the model parameters determining a relationship between V _GS -φ _s, and modeling the results specified V _GS -φ _s relationship to channel switching, based on FIG. A detailed method of modeling channel mobility will be described later with reference to FIG. 8.

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 this matching process is a result of the energy level mapping of the state density accurately, and is output as the final state density indicating the electrical characteristics of the amorphous semiconductor TFT.

Meanwhile, in order to determine the final state density, it is preferable to repeatedly adjust the above parameters until the channel mobility modeled in step 140 matches the channel mobility measured in step 115. This iteration naturally verifies the agreement between the modified model and the measurement results, so that accurate simulation results can be obtained even when the determined final state density is used for circuit simulation for the amorphous semiconductor TFT. In other words, the final state density can be utilized as a reliable model parameter for circuit simulation.

FIG. 5 is a flowchart illustrating a method of determining a final IV model in a method of calculating electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention, and further adding steps to steps 110 to 130 described in FIG. 1. Include. For convenience, only the process after step 130 will be described for convenience.

In step 117, the correlation between the current and voltage of the amorphous semiconductor TFT (hereinafter referred to as I-V characteristic) is measured and received. This I-V characteristic will be able to receive the measurement result with 110 steps.

In step 160, the IV characteristic is modeled from the state density using the parameter determined by the state density calculated in step 130. The state density modeling method proposed in relation to Equation 3 to Equation 5 above assumes that the gate voltage V _GS and the interfacial potential φ _s are simply proportional to each other. Explained that modifications are necessary. 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 detailed method of modeling the IV characteristic will be described later with reference to FIG. 8.

The final I-V model is determined by matching the I-V characteristics modeled in steps 170 and 160 with the I-V characteristics measured in step 117. Since the I-V model determined through this matching process is the result of the energy level mapping of the state density accurately, it is output as the final I-V model indicating the electrical characteristics of the amorphous semiconductor TFT.

Meanwhile, in order to determine the final I-V model, it is preferable to repeatedly adjust the parameter until the I-V characteristic modeled in step 160 matches the I-V characteristic measured in step 117. This iteration naturally validates the agreement between the modified model and the measurement results, so that accurate simulation results can be obtained even when the final I-V model determined is used for circuit simulation for the amorphous semiconductor TFT.

One consideration is the effect of source / drain parasitic resistance R _P , including contact resistance. With regard to the actual electrical characteristics, the amorphous oxide semiconductor TFT having a low channel resistance is more sensitive to the parasitic resistance R _P than the monocrystalline oxide semiconductor TFT due to the high channel mobility μ _CH . For example, a-GaInZnO TFTs have much greater influences on electrical characteristics of parasitic resistances such as contact resistance and source / drain spreading resistance than CMOS devices.

Therefore, in calculating the electrical characteristics of the amorphous semiconductor TFT targeted by the embodiments of the present invention, it is necessary to fully consider the influence of parasitic resistance. 6 is a cross-sectional view of an amorphous semiconductor TFT for explaining a method of calculating a parasitic resistance in the amorphous semiconductor TFT, wherein the contact resistance is denoted by R _C , the source / drain diffusion resistance is denoted by R _SP , and the channel resistance is denoted by R _CH . These resistors are factors that affect the parasitic resistance R _P , and hereinafter, a clear process for calculating the parasitic resistance R _P using these factors as parameters is presented.

In particular, in the case of a short channel TFT, the influence of parasitic resistance is further increased. Furthermore, the contact of the TFTs is non-linear because it is close to Schottky, 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 a gate-source It is a function sensitive to voltage V _GS , drain-source voltage V _DS, and channel length L. Modeling the short channel effect and intrinsic channel of the TFT requires a simple and accurate method of extracting R _P (V _GS , V _DS ).

In an 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 curves for various V _DS . Suggest how to. Assuming that the channel resistance r _CH per unit channel length and the parasitic resistance r _p per unit spreading path (L _SD ) are irrelevant for two Ls with small differences, R measured for both L1 and L2 cases _T1 and R _T2 may be described as in Equation 6 below.

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

By using the above calculation method, it is easy to use only two TFTs having different L, and R _P (V _GS , V _DS ) can be extracted.

FIG. 7 is a diagram illustrating a result of calculating parasitic resistance and total resistance using a method of calculating electrical characteristics of an amorphous semiconductor TFT according to another embodiment of the present invention, and using a-GaInZnO TFT as an amorphous semiconductor TFT. The results of calculating R _P (V _GS , V _DS ) and R _T (V _GS , V _DS ) are shown.

As described above, in the method of modeling the I-V characteristic according to the exemplary embodiment of the present invention, the parasitic resistance may be calculated from the transition curve of the TFT, thereby providing a model accurately reflecting the internal voltage applied to the TFT.

Meanwhile, the determination of the relationship V _GS −φ _s in FIG. 5 may be performed simultaneously with the channel mobility determination described above with reference to FIG. 4. 4 and 5, the state density is calculated through step 130, and the state density and the IV characteristic are modified through the V _GS −φ _s relationship, respectively. Therefore, the final V _GS -φ _s , the final state density and the final IV model can be determined simultaneously by adjusting the parameters in FIGS. 4 and 5, and these results are accurate model parameters that can be utilized for simulation for amorphous semiconductor TFTs. Is output. Hereinafter, algorithms for calculating the electrical characteristics of the amorphous semiconductor TFT described above will be described in order using mathematical equations. Equations to be described below are based on what has already been described above, or are arranged to comply with each process of FIG. 8 for convenience.

8 is a flowchart illustrating a specific method of calculating an electrical characteristic of an amorphous semiconductor TFT. The measurement value 810 is input and calculated according to an electrical characteristic calculation method 820, and as a result, a model parameter 830 is output. The process of doing so is shown. In FIG. 8 μ _BAND is conduction band mobility, μ _CH is intrinsic channel mobility, N _C is conduction band effective states, and E _FO is the equilibrium Fermi level. (equilibrium Fermi-level), φ _S is the surface potential, R _P is the source / drain parasitic resistance, φ _SS is the source channel potential, and φ _SD is the drain channel potential channel potential), and V _DS 'represents the internal voltage of V _DS .

First, in operation 810, I-V characteristics, C-V, and Hall effects are measured and input to TFTs under specific process conditions.

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

The state density value thus calculated is defined as the state density value, but it has been described above that the energy density mapping of the state density is not completed due to 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, a correction is necessary when energy level mapping the state density calculated by photocharge pumping.

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

In step 825, the channel mobility is modeled using the following equation (10) from the V _{GS -} φ _s relationship.

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

Here, an embodiment of the present invention matches the modeled channel mobility to the actual measured channel mobility. That is, the V _GS is used to model the channel mobility _- will be capable of modeling the best available channel mobility in the measured channel mobility by modifying the relation φ _s. 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 parameters 827 of the state density used prior to modeling channel mobility to be modified again to match the measured channel mobility and the modeled channel mobility. Thus, an embodiment of the present invention utilizes an iteration technique to modify these parameters 827.

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

In this way, the modeling I-V characteristic is compared with the measured value of the input I-V characteristic again in step 810. That is, the modeling parameters 827 are modified to match the I-V characteristics modeled in step 826 to the I-V characteristics measured in step 810. These parameters are modified through repetition as described previously in the method of matching channel mobility.

Eventually, according to this iteration technique, iteratively vary the parameters until the channel mobility μ _CH (V _GS ) calculated from the state density parameters 827 and the modeled IV coincide with the corresponding measured values. Done. When the final state density is determined through this iteration, since the agreement with the measurement result is naturally verified during the iteration, the channel mobility μ _CH (V _GS ) is determined at the moment when the final state density is determined, and step 830 is performed. The final V _{GS -} φ _s relationship and final IV characteristics are output simultaneously.

The embodiment of the present invention enables the modeling of the amorphous semiconductor TFT, which means that it is possible to establish model parameters for circuit simulation.

FIG. 9 is a diagram illustrating an apparatus 900 for calculating electrical characteristics of an amorphous semiconductor TFT according to an exemplary embodiment of the present invention, wherein the input unit 910, the modeling unit 920, the calculating unit 930, and the determining unit ( 940). This embodiment is implemented as an apparatus corresponding to the method of FIGS. 1, 4, and 5 described above, and only the features of the apparatus will be described herein, and a description of a specific operation method is omitted.

The input unit 910 irradiates light to the amorphous semiconductor TFT to measure the optical response characteristic of the C-V, and receives the result. In addition, the input unit 910 may measure the channel mobility of the amorphous semiconductor TFT in connection with the channel mobility modeling and receive the result. The input unit 910 may measure the IV characteristic of the amorphous semiconductor TFT in connection with the IV characteristic modeling to obtain the result. Can be input. The input unit 910 may be a device that physically measures and receives an object, but may also include various communication means for receiving the measured result 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 the capacitance as a function of C-V. In addition, in terms of channel mobility, the channel mobility may be modeled from the state density using the parameter of the state density, and in relation to the I-V characteristic, the I-V characteristic may be modeled from the state density using the parameter of the state density. As described above, the modeling unit 920 performs modeling of the CV, channel mobility, and IV characteristics in electronic form through various equations derived from the physical characteristics of the amorphous semiconductor TFT. It may be implemented as a processor or an equivalent calculator. Of course, memory may be utilized for additional computations to perform these modelings.

The calculator 930 receives the measured optical response characteristic and calculates the state density by combining the model with the modeled function through the modeling unit 920. The calculator 930 may also be implemented as a processor of a conventional computer system or an equivalent.

The determiner 940 may 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. Both the channel mobility and the IV characteristics can match the modeled value by the repetitive modification of the state density to the measured value, and both modeling results are changed by the parameter of the state density. And both IV characteristics. Therefore, if a parameter of the state density in which both the modeled value and the measured value match are found, the final state density and the final I-V characteristic may be determined and output as a result value through the determination unit 940. The determination unit 940 may also be implemented as a processor of a conventional computer system or an equivalent.

Although the modeling unit 920, the calculation unit 930, and the determination unit 940 described above are conceptually separated from each other due to functional differences, all of these configurations are implemented as a general-purpose processor and a storage space for processing electronic data. Could be.

Meanwhile, the present invention can be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system.

Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which may also be implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. 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 thereof. Those skilled in the art will understand that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

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

FIG. 2 is a view for explaining a method of extracting state density using photo charge 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.

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

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

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

5 is a flowchart illustrating a method of determining a final I-V model in a method of calculating electrical characteristics 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 the amorphous semiconductor TFT.

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

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

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

Claims (11)

In the method for calculating the electrical characteristics of the amorphous semiconductor TFT, Irradiating light to the TFT to measure and receive an optical response characteristic of C-V; Modeling each of the capacitances of the non-irradiated light and the irradiated light as a function of C-V; And Combining the measured optical response characteristic with the modeled function to calculate a state density. The method of claim 1, Measuring the optical response characteristics of the C-V, Irradiating the TFT with photons having an energy less than an energy bandgap of the amorphous semiconductor; And Measuring a change in the optical response characteristic of the C-V after irradiation compared to before the photon irradiation. The method of claim 1, Measuring and receiving channel mobility of the TFT; Modeling 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. The method of claim 3, wherein Determining the final state density repeatedly adjusts the parameter until the modeled channel mobility matches the measured channel mobility. The method of claim 1, Measuring and receiving an I-V characteristic of the TFT; Modeling I-V characteristics from the state density using predetermined parameters; And Determining the final I-V model by matching the modeled I-V characteristic with the measured I-V characteristic. The method of claim 5, Determining the final I-V model is characterized by iteratively adjusting the parameter until the modeled I-V characteristic matches the measured I-V characteristic. The method of claim 5, The modeling of the I-V characteristic may include modeling 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 having recorded thereon a program for executing the method of claim 1 on a computer. In the apparatus for calculating the electrical characteristics of the amorphous semiconductor TFT, An input unit which receives the TFT to measure light response characteristics of the C-V and receives the light; A modeling unit for calculating each of the capacitances when no light is irradiated with light and modeling the capacitance as a function of C-V; And And a calculator configured to receive the measured optical response characteristics and calculate a state density in combination with the modeled function. The method of claim 9, The input unit is input by measuring the channel mobility of the TFT, The modeling unit models a 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. The method of claim 9, The input unit is input by measuring the I-V characteristics of the TFT, The modeling unit models an 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.

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