Electron density of the two-dimensional electron gas in modulation doped layers

Abstract

The electron density of the two-dimensional electron gas in modulation doped structures is calculated as a function of the doping density in (Al,Ga)As, the thickness of the undoped (Al,Ga)As layer, the lattice temperature, and other device parameters. The results of the calculation show that the depletion approximation is not accurate enough and that the Fermi-Dirac statistics (rather than the Boltzmann statistics) should be used in the calculation. A simple analytical model which takes these factors into account is shown to be in good agreement with our computer calculations and experimental data. The obtained results may be used to evaluate the maximum intrinsic transconductance and the maximum gate voltage swing for the modulation doped field effect transistors.