Selective Growth of GaAs on GaAs (111)B Substrates by Migration-Enhanced Epitaxy

Selective epitaxial growth of GaAs on GaAs (111)B substrates masked by SiO2 has been demonstrated by using migration-enhanced epitaxy (MEE) with annealing after deposition of either Ga or As4. When annealing is performed after Ga deposition, no polycrystalline GaAs is formed on the SiO2 mask and the surface of the epitaxial layer grown in the window region is very smooth and uniform, whereas polycrystalline deposition occurs when the annealing is performed after As4 deposition. These results indicate that complete selectivity is more easily obtained by annealing after Ga deposition rather than As4 deposition. By using this method successful selective growth of GaAs has been achieved at substrate temperature around 590°C. Ga adatoms deposited on the SiO2 mask seem to evaporate or diffuse into the window region during the Ga deposition and annealing period. The conditions for successful selective growth has been established as a function of substrate temperature and Ga flux, so that smooth epitaxial layers are grown reproducibly. We also discuss the surface diffusion of Ga atoms on the SiO2 mask.