Characterization of in situ etched and molecular beam epitaxy regrown GaAsinterfaces using capacitance-voltage measurements, far infrared spectroscopy, and magnetotransport measurements

In this study, we characterize GaAs interfaces processed by ion beam etchin g (IBE), chemical assisted ion beam etching (CAIBE), and chemical gas etchi ng (CGE). The etched interfaces are overgrown with GaAs or AlGaAs using mol ecular beam epitaxy. Interfaces in Si-doped GaAs are characterized with cap acitance-voltage (C-V) profiling. Furthermore, we use a two-dimensional ele ctron gas (2DEG), located directly at the etched interface in modulation do ped AlGaAs/CaAs heterostructures, to probe the interface quality with far i nfrared (FIR) transmission spectroscopy and magnetotransport measurements. Applying a CGE process with suitable parameters we can remove more than 100 nm GaAs and generate clean surfaces with 2DEGs similar to those of nonetch ed reference samples. in addition we can reduce the interface state density of an IBE or CAIBE etched surface significantly applying a subsequent CGE process, which removes the ion damaged layer. However the two-dimensional e lectron systems at such interfaces show characteristic FIR absorption of do t-like potentials, which is a clear sign of a contaminated or disturbed sur face. (C) 2000 American Vacuum Society.