Two-dimensional growth mode promotion of ZnSe on Si(111) by using a nitrogen substrate surface treatment

The growth mode of ZnSe epilayers prepared by pulsed molecular beam epitaxy (MBE) on Si(111) substrates, irradiated with a plasma of nitrogen (N-plasm a) prior to the deposition, was compared to that of ZnSe epilayers prepared by conventional MBE directly on untreated Si substrates. Spotty reflection high-energy electron diffraction (RHEED) patterns with a diffuse backgroun d were observed during the initial stages of the conventional MBE growth. I n sharp contrast, the RHEED patterns during the pulsed MBE growth on the N- plasma treated Si surface showed very well-defined streaks, and moreover a two-fold reconstruction was observed indicating an atomically flat surface. A strong evidence of the improved epitaxy, and the two-dimensional nucleat ion obtained by this technique was the clear presence of large amplitude RH EED oscillations. AFM images confirmed a flatter ZnSe surface for this samp le. (C) 1999 Elsevier Science B.V. All rights reserved.