Observation of oxygen contamination at ZnSe/GaAs interfaces using SIMS

ZnSe epilayers were grown on GaAs (1 0 0) substrates using MBE. The native contamination (oxide and carbon) was removed in situ from the substrate surfaces by conventional thermal cleaning and by exposure to atomic hydrogen. A maximum substrate temperature of 600 °C was required for the thermal cleaning process, while a substrate temperature of 450 °C was sufficient to clean the substrate using hydrogen. ZnSe epilayers were also grown on As capped GaAs epilayers, which were decapped at a maximum temperature of 350 °C. SIMS profiles showed the existence of oxygen at the interface for all of the substrate preparation methods. The oxygen surface coverage at the interface was found to be 0.03% for the atomic hydrogen cleaned substrate and 0.7% for the thermally cleaned substrate.