Correlation Between Carrier Concentration Distribution, I–V and C–V Characteristics of a-InGaZnO TFTs

In this work, a technology computer-aided design (TCAD) device model based on an fabricated amorphous InGaZnO thin-film transistor (a-IGZO TFT) was established to study the correlation between carrier concentration distribution, current-voltage (I-V) and capacitance-voltage (C-V) characteristics of a-IGZO TFTs. The equilibrium carrier concentration of the a-IGZO layer influenced by defect states, interface fixed charges, gate and S/D electrodes were studied systematically and quantitatively. The a-IGZO thickness was varied from 10 nm to 140 nm. The doping concentration in the bulk a-IGZO layer and source/drain (S/D) contact regions were changed from 10
¹⁰
cm
^-3
to 10
²⁰
cm
^-3
. The physical mechanisms underlying the I-V and C-V variation caused by above-mentioned parameters were explored by analyzing the energy band diagram and carrier concentration distribution in the a-IGZO layer. The total number of electrons in the channel region of the TFT was calculated by numeric integration for further investigation of its correlation with the a-IGZO thickness, I-V, and C-V characteristics of the a-IGZO TFTs.