Infra-red absorption spectroscopy, optical transient current spectroscopy and photoluminescence spectroscopy were used to investigate the annealing-induced evolution of defects in low-temperature grown GaAs-related materials. Low-temperature samples of bulk GaAs and GaAs/AlGaAs multiple quantum-well structures were grown, at 220 and 320C, onto (001)GaAs substrates, respectively. A strong defect-related absorption band was observed in both as-grown samples. It became weaker in samples which were annealed at above 600C. In bulk GaAs samples which were annealed at 600 to 800C, a large negative decay signal of the optical transient current was observed which made it difficult to identify deep levels. At annealing temperatures of 600 and 700C, both AsGa antisites and small As cluster-related deep levels were identified in GaAs/AlGaAs samples. It was found that, compared to the As cluster, the AsGa antisite had a larger activation energy and carrier capture rate. At an annealing temperature of 800C, the large negative decay signal was also observed in GaAs/AlGaAs samples. It was argued that this negative decay signal was related to large As clusters. In the case of GaAs/AlGaAs samples, transient photoluminescence spectra revealed the effect of defect evolution upon optical properties. The results clearly indicated an evolution from AsGa antisites to As clusters after annealing.

Annealing-Induced Evolution of Defects in Low-Temperature Grown GaAs-Related Materials. M.H.Zhang, L.W.Guo, H.W.Li, W.Li, Q.Huang, C.L.Bao, J.M.Zhou, B.L.Liu, Z.Y.Xu, Y.H.Zhang, L.W.Lu: Physical Review B, 2001, 63[11], 115324 (6pp)