Calculation of electron density in planar-doped high electron mobility transistors

We analyze δ-doped High Electron Mobility Transitor (HEMT) structures by solving Schrödinger's equation and Poisson's equation self-consistently in one-dimension. The two equations are solved iteratively using the fixed convergence factor scheme. We consider the V-shaped quantum well formed by the δ-doped layer in addition to the "channel" quantum well. In practical devices, the population of the V-shaped quantum well should remain low. We study the effect of different spacer thicknesses on this population and also on the maximum achievable channel electron density. We describe the results for two structures that have been reported in the literature and show that the device performance can vary significantly with respect to parameters such as spacer thickness and doping density. Further, in the case of a double heterojunction structure with doping on either side, we show that the result of increased doping can be quite different depending on which δ-doped layer has larger doping density.