Effects of AlAs interfacial layer on material and optical properties of GaAs∕Ge(100) epitaxy

Abstract

Ga As ∕ Al As ∕ Ge ( 100 ) samples grown at 650°C with AlAs interfacial layer thickness of 0, 10, 20, and 30nm were characterized using transmission electron microscopy, secondary ion mass spectrometry (SIMS), and photoluminescence (PL) techniques. SIMS results indicate that the presence of an ultrathin AlAs interfacial layer at the GaAs∕Ge interface has dramatically blocked the cross diffusion of Ge, Ga, and As atoms, attributed to the higher Al–As bonding energy. The optical quality of the GaAs epitaxy with a thin AlAs interfacial layer is found to be improved with complete elimination of PL originated from Ge-based complexes, in corroboration with SIMS results.