On the capacitance-voltage modeling of strained quantum-well MODFETs

A theoretical model for the capacitance-voltage characteristics of strained modulation-doped field-effect transistors (MODFETs) is developed, based on a self-consistent solution of the Schrodinger and Poisson equations. We report on the first MODFET C-V simulator in which the proposed Hamiltonian takes into account the strain caused by lattice mismatch, as well as the position-dependent lattice constant and electron effective mass. It is demonstrated that the inclusion of strain-related energy terms is essential to achieve good agreement between theory and experimental data for the C-V characteristics of pseudomorphic-channel devices at high gate voltages. The model is also shown to be a useful tool to predict important device characteristics such as the transconductance.