NUMERICAL-SIMULATION F BACKGATING SUPPRESSION IN HIGH-ELECTRON-MOBILITY TRANSISTORS (HEMTS) WITH A LOW-TEMPERATURE MOLECULAR-BEAM EPITAXY (MBE)-GROWN GALLIUM-ARSENIDE BUFFER LAYER BETWEEN THE SUBSTRATE AND ACTIVE LAYERS

Numerical simulations were carried out for a high electron mobility tr ansistor (HEMT) in which the active device was separated from the hole -trap-rich substrate by a gallium arsenide buff er layer, grown by mol ecular beam epitaxy at low temperature, which contains the EL3 electro n trap. The results show, for the first time, that the interface betwe en the substrate and the buffer layer behaves like a reverse biased p- n junction when a negative backgate voltage is applied. By sustaining the backgate voltage across it, this junction effectively isolates the active channel of the HEMT from the substrate bias and thus eliminate s backgating in the device.