Thermal annealing effect on the properties of GaBiAs

The influence of thermal annealing on optical properties and carrier lifetime of dilute GaBixAs1‐x layers was investigated. Thick (0.5‐1.5 μm) relaxed and thin (30‐100 nm) strained bismide layers were grown onto semi‐insulating (100)‐oriented GaAs substrates by molecular beam epitaxy (MBE) using As4 and As2, respectively. The post‐growth annealing was carried out in the rapid thermal annealing (RTA) oven at the temperatures ranging from 550 °C to 750 °C under nitrogen atmosphere. The high resolution X‐ray diffraction (HRXRD), photoluminescence (PL) and optical pump‐THz probe measurements revealed two different GaBixAs1‐x anneal mechanisms. The annealing at temperatures higher than 600 °C caused a significant reduction of carrier lifetime of relaxed bismide layers with x > 0.05. Meanwhile, thick layers with a smaller content of Bi (x < 0.05) and thin strained layers annealed up to 600 °C still exhibited long carrier lifetimes. On the other hand, the significant photoluminescence signal increase at room and liquid nitrogen temperatures was observed for the GaBiAs layers grown using As2 (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)