ELECTRODE INTERDEPENDENCE AND HOLE CAPACITANCE IN CAPACITANCE-VOLTAGECHARACTERISTICS OF HYDROGENATED AMORPHOUS-SILICON THIN-FILM-TRANSISTOR

The interelectrode capacitance-voltage (C-V) characteristics of back-c hannel-etched inverted-staggered hydrogenated amorphous silicon (a-Si: H) thin-film transistors (TFTs) were investigated. It is demonstrated that this simple measurement can be used to diagnose TFT parameters su ch as the fabricated channel length,the channel resistance, and the er ror in the mask alignment of the source and drain overlap lengths. The C-V characteristics associated with the hole accumulation in a-Si:H T FTs with n(+)-type source/drain contacts were also examined. We observ ed that the ac capacitance increases for low frequencies and/or modera tely high measurement temperatures provided the gate voltage is suffic iently negative. One possible mechanism for this hole capacitance is p roposed that accounts for the observed frequency and temperature depen dence. (C) 1998 American Institute of Physics.