Inversion and Accumulation Layer Formation at Elevated Temperatures in n GaAs-Anodic Oxide MIS Devices.

摘要

At room temperature nGaAs-anodic oxide MIS devices typically exhibit some form of deep-depletion mode operation which is characteristic of a low thermal generation rate for minority carriers in the semiconductor. In addition, for accumulation mode bias voltages the small signal capacitance often does not approach the oxide capacitance, instead exhibiting a dispersion whereby this capacitance varies with the frequency of the a-c signal and the sweep-rate of the d-c bias voltage. In this paper, capacitance-voltage measurements are reported for nGaAs-anodic oxide MIS devices taken at elevated temperatures with varying d-c bias voltage sweep rates. The formation of a stable inversion layer even at high sweep rates and the elimination of accumulation capacitance dispersion for a C-V measurement frequency of up to 1 MHz is observed at temperatures above room temperature. At high temperatures and slow sweep-rates, considerable mobile ion motion in the oxide is observed. A discussion of this observation based on recently developed theories for oxide growth is presented. (Author)