Deep-level transient spectroscopy study of electron traps in rapid thermally annealed SiO 2-capped n-type GaAs layers grown by metalorganic chemical vapour deposition

Abstract

Three dominant electron traps S1 ( E c−0.23 eV), S2* ( E c−0.53 eV), and S4 ( E c−0.74 eV) are introduced in SiO 2/n-GaAs after rapid thermal annealing (RTA). A defect S3 ( E c−0.72 eV) is observed in uncapped and annealed samples only. The S2* arises from the superposition of two defects, of which S2 ( E c−0.46 eV) can be resolved using filling pulse widths <1 ms. The intensities of S1, S2*, and S4 show Arrhenius-like dependencies on the RTA temperature. We argue that the defects are formed as a result of an increase in the ratio of As : Ga in the near-surface region of the GaAs layers. The electronic and annealing properties of S4 show that it is a member of the EL2 family of defects. The removal of S1 and S2*, as well as the introduction of secondary defects, during isochronal annealing experiments is also discussed.