Reconstructions of GaAs and AlAs surfaces as a function of metal to As ratio

Abstract

The room temperature surface reconstructions of GaAs and AlAs have been investigated with angle integrated photoemission as a function of the metal to arsenic ratio. Detailed information on both the (110) and (100) surface as a function of reconstruction has been obtained from changes in the surface core level intensities, binding energy shifts, and changes in the surface valence band density of states. The GaAs(100) surface shows ordered reconstructions over a wide composition range. The ordering proceeds through a series of centered structures formed from As and vacancies in the outer layer in the As rich range to noncentered structures derived from As, Ga antisite defects, and vacancies on the Ga rich end. The AlAs(100) surface is predominantly disordered and only a 3×2 reconstruction was found in a narrow composition range. Aspects of the Al–Ga exchange reaction on GaAs(110) are discussed.