Title :
Threshold voltage, field effect mobility, and gate-to-channel capacitance in polysilicon TFTs
Author :
Jacunski, Mark D. ; Shur, Michael S. ; Hack, Michael
Author_Institution :
Dept. of Electr. Eng., Virginia Univ., Charlottesville, VA, USA
fDate :
9/1/1996 12:00:00 AM
Abstract :
Based on experimental and theoretical studies of n- and p-channel polysilicon thin film transistors with gate W/L ratios from 0.3 to 3.3, we have demonstrated that the threshold voltage extracted from gate to channel capacitance data results in field effect mobility parameters which are independent of device geometry. The parameters extracted using this Vt allow us to reproduce the I-V characteristics of the n- and p channel TFTs over wide ranges of bias voltages and gate sizes. The Cgc-VGS characteristics of polysilicon TFTs are strongly affected by the trapping and de-trapping of carriers. As a result, the measured Cgc characteristic is a function of measurement frequency and gate length. However, we demonstrate that to the first order, the frequency dispersion of the Cgc curve can be related to the effective carrier transit time determined using the VGS dependent field effect mobility
Keywords :
capacitance; carrier mobility; electron traps; elemental semiconductors; hole traps; insulated gate field effect transistors; silicon; thin film transistors; I-V characteristics; Si; bias voltages; de-trapping; effective carrier transit time; field effect mobility; gate length; gate-to-channel capacitance; measurement frequency; n-channel thin film transistors; p-channel thin film transistors; polysilicon TFTs; threshold voltage; trapping; Capacitance; Computer hacking; Data mining; Frequency measurement; Grain boundaries; Knee; Length measurement; Senior members; Thin film transistors; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
