AN INVESTIGATION OF THE EARLY STAGES OF NATIVE OXIDE-GROWTH ON CHEMICALLY ETCHED AND SULFUR-TREATED GAAS(100) AND INP(100) SURFACES BY SCANNING TUNNELING MICROSCOPY

The growth of native Oxides on the GaAs(100) and InP(100) chemically etched surfaces, following exposure to air, has been investigated by scanning tunnelling microscopy (STM). These studies provide information on both the rate and progression of the native oxide growth over 100 X 100 nm2 areas of the semiconductor surfaces. The rate of oxide growth on the GaAs etched surface was found to be significantly faster than on the InP surface. On both semiconductor surfaces the oxide growth was observed to proceed via nucleation centres dispersed across the surface which eventually coalesced to form a uniform oxide layer approximately 2 nm thick. Attempts were made to reduce the rate of native oxide growth by treating the chemically etched surface with ammonium sulfide prior to air exposure. This resulted in a significant reduction in oxide growth rate on both surfaces with a thinner oxide forming on the InP surface.