Selective area MBE of GaAs, AlAs and their alloys by periodic supply epitaxy

Abstract

Selective area epitaxy (SAE) of GaAs, AlAs and (AlGa)As by molecular beam epitaxy (MBE) was successfully achieved by employing periodic supply epitaxy (PSE) in which group III flux is sent in pulse under a continuous group V flux. Smooth and flat surface was obtained in the window area on (001) and (111)B substrates and strong enhancement of selectivity was observed by increasing the ratio of the group III flux interruption time to the deposition time. However, the substrates of (110), (111)A and (411)A gave the layers with less smoothness. SAE of AlAs and (AlGa)As by PSE was conducted at 640°C and complete selectivity was obtained by decreasing the growth rate or partial growth rate of AlAs. It was found that in PSE of (AlGa)As, the Al flux uniquely determines the selectivity and depleted zone width. PSE was applied to fabricate submicron structures. An array of lines with less than 0.5 μm. in width has been successfully grown without any polycrystal deposits on the mask.