Charge dynamics in heterostructure Schottky-gate capacitors and their influence on the transconductance and low-frequency capacitance of MODFETs

The authors present a computer investigation of the gate capacitance and transconductance characteristics of MODFETs and related capacitors. The quantum-mechanically predicted behavior of single- and multiple-heterostructure transistors is in excellent agreement with experiments presented in the literature. The donor level energy is shown to affect the transconductance and capacitance characteristics directly. The capacitance of multiple-heterojunction devices is predicted to exhibit a staircase nature with possible applications in n-ary logic circuits. A critical analysis of the application of C-V profiling techniques to heterostructure capacitors is also presented