THE IMPORTANCE OF CONTACT INJECTION IN UNDOPED ALGAAS/GAAS HETEROSTRUCTURES

We have used a two-dimensional finite-difference analysis to simulate the current flow and charge distribution in undoped Al-GaAs/GaAs MODFET structures called insulated-gate field-effect transistors (HIGFET's). We have studied how an electron channel can be induced at the AlGaAs/GaAs interface when there is no doped supply layer. We have studied the origins of the charge in this channel by comparing its behavior in equilibrium with that when a current flows. By considering different geometries of a Schottky gate and implanted source and drain contacts, we show clearly the inter-relationship between gate control and electron injection from the doped contact regions and give a graphic view of the origins of the interfacial charge in a HIGFET. © 1990 IEEE