Electrical Properties of Interface-Traps in Selectively Doped AlGaAs/GaAs Heterostructures

A hole-trap-like peak appears in the drain current DLTS spectra recorded from a high-electron-mobility transistor fabricated with a selectively doped AlGaAs/GaAs heterostructure grown by molecular-beam epitaxy. The peak is caused by traps which strongly affect the mobility. The emission and the capture activation energy of the traps increases as the gate bias increases. This shows that the traps which remain ata fixed energy level relative to the GaAs conduction band edge exchange electrons with the sub-bands in the accumulation layer. Based on the above characteristics, an analysis of the spectra indicates that interface-traps with a density of 3.8×10 10 cm -2 are located at 0.01 eV above the conduction band edge of GaAs, in the potential well of the accumulation layer.