Characterization of Polycrystalline Silicon Thin-Film Transistors

概要

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The nonlinear behavior of the transfer characteristics of polycrystalline silicon thin-film transistors (poly-Si TFTs) at the threshold voltage was analyzed. The threshold voltage $V_{\text{T}}$ was defined as the gate voltage giving half of the maximum transconductance ($G_{\text{mMAX}}/2$). The nonlinear parameter $\Delta V$ was also introduced as the maximum transconductance divided by the differential of $G_{\text{m}}$ at $V_{\text{T}}$. $V_{\text{T}}$ and $\Delta V$ increased as the density of defect states increased. Moreover, $\Delta V$ increased as the energy level of defects increased near the band edge. $\Delta V$ gave the carrier density and the Fermi level at the silicon surface at $V_{\text{T}}$. $V_{\text{T}}$ and $\Delta V$ also gave the density of occupied defects states at $V_{\text{T}}$. Analysis using $V_{\text{T}}$ and $\Delta V$ was applied to the characterization of n-channel TFTs fabricated with laser crystallization and H2O vapor annealing. $V_{\text{T}}$ and $\Delta V$ were 0.90 and 0.81 V, respectively. They gave the Fermi level and the densities of electron carrier and occupied defect states at the threshold voltage as 0.91 eV, $2.2\times 10^{10}$ and $1.8\times 10^{11}$ cm-2, respectively.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-03-15