Published online by Cambridge University Press: 26 February 2011
Deep levels in the annealed low-temperature molecular beam epitaxial (LT-MBE) GaAs layer were successfully characterized by using the capacitance deep-level transient spectroscopy (C-DLTS) as well as photocapacitance quenching technique in combination with a unique sample structure. In this work, we have fabricated the samples by inserting the LT-GaAs layer into two n-type semi-conductive layers, like a sandwich (n-LT-n structure), grown at normal substrate temperatures. DLTS measurements have revealed that one electron trap dominates the annealed LT-MBE GaAs. The dominant electron trap was very similar to the so-called EL3 level. Moreover, we found the midgap level appeared upon 800-900°C RTA, although no midgap level was detected in the as-grown n-LT-n sample (annealed at 620°C) and confirmed with photoquenching measurements that it is the EL2 level.
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