In-situ deposition of Ga2O3, SiO2, and MgO films on clean, atomically
ordered (100) GaAs surfaces grown by molecular beam epitaxy using a mu
ltiple-chamber ultra high vacuum system has been investigated. Using t
his technique, direct bonding of oxide molecules to GaAs surface atoms
revealing intrinsic oxide-GaAs interface properties has been achieved
, The GaAs surface reconstruction prior to deposition as observed by r
eflection high energy electron diffraction and the chemical shift of t
he interfacial As 3d core level acquired by X-ray photoelectron spectr
oscopy depth profiling are clearly correlated. AsxOy, or elemental As
were not detectable at in-situ fabricated oxide-GaAs interfaces. In sh
arp contrast to SiO2- and MgO-GaAs interfaces which are characterized
by a Fermi level intrinsically pinned at midgap, Ga2O3-GaAs interfaces
exhibit unique intrinsic electronic properties including an interface
state density and recombination velocity in the mid 10(10) cm(-2) eV(
-1) range and of 4500 cm/s, respectively.