Modeling of current-voltage characteristics for dual-gate amorphous silicon thin-film transistors considering deep Gaussian density-of-state distribution

Jian Qin; Ruohe Yao

doi:10.1088/1674-4926/36/12/124005

J. Semicond. > 2015, Volume 36?>?Issue 12?> 124005

SEMICONDUCTOR DEVICES

Modeling of current-voltage characteristics for dual-gate amorphous silicon thin-film transistors considering deep Gaussian density-of-state distribution

Jian Qin^{1, 2} and Ruohe Yao^1,

+ Author Affiliations

Corresponding author: Yao Ruohe,Email:gzu_jyuan@163.com

DOI: 10.1088/1674-4926/36/12/124005

Abstract: Accounting for the deep Gaussian and tail exponential distribution of the density of states, a physical approximation for potentials of amorphous silicon thin-film transistors using a symmetric dual gate(sDG a-Si:H TFT) has been presented. The proposed scheme provides a complete solution of the potentials at the surface and center of the layer without solving any transcendental equations. A channel current model incorporating features of gate voltage-dependent mobility and coupling factor is derived. We show the parameters required for accurately describing the current-voltage(I-V) characteristics of DG a-Si:H TFT and just how sensitively these parameters affect TFT current. Particularly, the parameters' dependence on the I-V characteristics with respect to the density of deep state and channel thickness has been investigated in detail. The resulting scheme and model are successively verified through comparison with numerical simulations as well as the available experimental data.

Key words: amorphous silicon thin-film transistor, dual gate, surface potential, density of states, Gaussian deep states, drain current

References

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[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
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[23]
[24]
[25]
[26]
[27]
[28]
[29]

Fig1. The discretization of deep Gaussian DOS for the analysis of the trap charge concentration.

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Fig2. Solutions of the difference in potential $\alpha$ as a function of the symmetrical gate voltage. Other DOS parameters used in this figure have been given in Table1.

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Fig3. Comparison results of the electric potentials as a function of gate voltage for various densities of Gaussian trap states. (a) $\[{{N}_{\text{G}}}=8.01\times {{10}^{16}}c{{m}^{-3}}e{{V}^{-1}}\]$ (extracted $V_{\rm FB}=$ 0.29 V). (b) $\[{{N}_{\text{G}}}=3.21\times {{10}^{17}}c{{m}^{-3}}e{{V}^{-1}}\]$ (extracted $V_{\rm FB}=$ 0.15 V)

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Fig4. Solutions of the surface potential $\[{{\phi }_{\text{s}}}\]$ as a function of gate voltage as obtained from this work. The results of $\[{{\phi }_{\text{s}}}\]$ for a single-gate TFT with the same DOS parameters are also shown for comparison. The calculation of the latter is based on Equation (35) from Reference~^[23]. Other DOS parameters used in this figure have been given in Table1.

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Fig5. Solutions of the surface potential $\[{{\phi }_{\text{s}}}\]$ as a function of gate voltage for various channel potentials. Other DOS parameters used in this figure have been given in Table1.

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Fig6. Normalized drain current as a function of effective gate voltage for various densities of N_G at a fixed drain voltage $\[{{V}_{ds}}\]$= 5 V,as calculated by this work (lines) and the 2-D numerical simulation (symbols) in log scale for comparison.

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Fig7. Normalized drain current as a function of effective gate voltage for various channel thicknesses at a fixed drain voltage $\[{{V}_{ds}}=\]$ 1V,as calculated by this work (lines) and the 2-D numerical simulation (symbols) in log scale for comparison.

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Fig8. Comparison results of drain current between the model (lines) and the published experimental data (symbols) from Reference ^[4]. The extracted parameters used for the model are listed as $t_{\rm si}=$ 200 nm,$W/L=$ 30/6 $\mu$m,$C_{\rm ox}=$ 2.85 $\times$ 10-8 F/cm²,$\[{{\mu }_{\text{o}}}\]$=18.5cm²/(V$\cdot$s),$g_{\rm t}=$ 1.3 $\times$ 1022 cm^-3eV^-1,T_t}=255 K,$V_{\rm FB}=$ 1.85 V,$N=10$,MX $=$ 1.

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Fig9. Comparison results of drain current between the model (lines) and the published experimental data (symbols) from Reference ^[19]. The extracted parameters used for the model are listed as $t_{\rm si}=$ 1 $\mu $m,$W/L=$ 168/10 $\mu $m,$C_{\rm ox}=$ 3.01 $\times$ 10^-8 F/cm²,$\[{{\mu }_{\text{o}}}\]$=13.3~cm²/(V$\cdot$s),$g_{\rm t}=2.2 $\times$ 10²² cm^-3eV^-1,T_t}=268 K,$V_{\rm FB $=2.35 V,$N=10$,MX $=$ 1. Other parameters are the same as the ones given in Table1.

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Table 1. Typical sDG a-Si:H TFT parameters used in study.

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[3]
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[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]

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Received: 21 May 2015 Revised: Online: Published: 01 December 2015

Accounting for the deep Gaussian and tail exponential distribution of the density of states, a physical approximation for potentials of amorphous silicon thin-film transistors using a symmetric dual gate(sDG a-Si:H TFT) has been presented. The proposed scheme provides a complete solution of the potentials at the surface and center of the layer without solving any transcendental equations. A channel current model incorporating features of gate voltage-dependent mobility and coupling factor is derived. We show the parameters required for accurately describing the current-voltage(I-V) characteristics of DG a-Si:H TFT and just how sensitively these parameters affect TFT current. Particularly, the parameters' dependence on the I-V characteristics with respect to the density of deep state and channel thickness has been investigated in detail. The resulting scheme and model are successively verified through comparison with numerical simulations as well as the available experimental data.

Modeling of current-voltage characteristics for dual-gate amorphous silicon thin-film transistors considering deep Gaussian density-of-state distribution

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