Redundant Sb condensation on GaSb epilayers grown by molecular beam epitaxy during cooling procedure

Abstract

The effect of four different cooling receipts on the surface morphologies of unintentionally-doped GaSb epilayers on GaSb (100) substrates grown by molecular beam epitaxy is reported. Those receipts include three different Sb beam equivalent pressure (BEP) levels and two different termination temperatures. Surface morphologies of epilayers were examined by wet etching, surface profiler, atomic force microscopy, scanning electron microscopy and Raman spectroscopy. The results demonstrate that during the cooling period, a Sb BEP of 4.00×10−4Pa at a termination temperature of 400°C induces a smooth surface without Sb condensation whereas same Sb BEP at a termination temperature of 350°C forms a 300nm thick Sb layer on the surface. In addition, it is revealed that by applying a wet etching procedure and using a surface profiler it is possible to identify this condensed layer from the two-sloped feature of mesa profile.