A closed-form expression to analyze electronic properties in delta-doped heterostructures

We develop a closed-form model to describe the electronic properties for delta modulation doped heterostructures, particularly the 2DEG sheet charge density and the electric field distribution in the direction of growth. The model includes the effects of real-space charge transfer and carrier degeneracy. The electron transfer and quasi-equilibrium condition in growth direction have been used in order to express the 2DEG sheet charge density that is only a function of material parameters and constants. An empirical constant, corresponding to quantized energy states, has been employed to further simplify this description and to arrive at a closed-form expression. Results from the analytical expressions are shown to agree well with numerical simulations based on a self-consistent solution of a modified Schrodinger and Poisson equations. In addition to their use in modeling of current conduction in modulation doped field effect transistors (MODFETs), we expect that these expressions would serve as versatile tools in the modeling of optical and spectral effects that occur in the AlGaAs/GaAs heterostructures. (C) 2004 Elsevier Ltd. All rights reserved.