Studies of the ZnSe/GaAs interface using SIMS

The studies reported here present data obtained from ZnSe epilayers grown on GaAs substrates by MBE. The native oxide and carbon were removed from the substrate surface in two different ways, by thermally cleaning up to around 600°C and by exposing substrates at 450°C to atomic hydrogen. As passivated GaAs epilayers have also been used as substrates to grow ZnSe epilayers. SIMS profiles showed the existence of oxygen at the interface for all substrate preparation methods. Depth profiles obtained from SIMS show the expected mixing of the two materials at the interface and evidence of interdiffusion across the interface. SIMS measurements are difficult to quantify due to the variations in the ionisability of different atoms and the effect of different matrices. Depth profiles can be broadened by curved craters and by intermixing due to ion collisions. The range of layer thicknesses and of interface widths available in this study enable the broadening effects to be quantified so that the atomic distributions in the different interfaces can be obtained