An analytical unified extraction method for the distribution and relaxation time of trap states by capacitance-conductance-voltage characteristics in metal oxide TFTs

Abstract This article proposes a method to simultaneously extract both the distribution and relaxation time of trap states by capacitance-conductance-voltage characteristics (CGV). Based on the SRH emission-capture model under small signals, a semiconductor physical equivalent circuit of TFTs taking into account the contact resistance is established. Poisson's equation and Gauss's theorem can relate the induced charge density in the channel to the gate capacitance, which can be divided into two parts, namely, the capacitance of free electron and the capacitance of trapped electron. Combined with the test results, the capacitance and resistance of trapped electron can be extracted separately. Further, the distribution and relaxation time of trap states can be obtained. Moreover, the CGV method is verified by comparing the results with those of other trap-state extraction methods.