Abnormal behavior of midgap electron trap in HB-GaAs during thermal annealing

Abstract

The behavior of the EL2 family in horizontal Bridgman-(HB) grown GaAs by two thermal annealing methods, furnace annealing and rapid thermal annealing, was studied through deep level transient spectroscopy (DLTS) measurements, and a similar behavior of another group of electron traps was observed. As the annealing time is increased, the EL2 trap (Ec-0.81 eV) is transformed to the new trap, EX2 (Ec-0.73 eV), and finally to the other new trap, EX1 (Ec-0.86 eV). Also the EL6 group (Ec-0.18, 0.22, 0.27, and 0.35 eV) varied similarly to the EL2 family as a trap (Ec-0.27 eV) is transformed to the first trap (Ec-0.18 eV) and then the second trap (Ec-0.22 eV). This result revealed that the EL2 family is related to the EL6 group. From the study of photocapacitance quenching, the existence of metastable states of the EL2 family is identified. These results suggest that the atomic structure of the EL2 trap may be an arsenic antisite with an interstitial arsenic and a double vacancy, such as VAsAsIVGaAsGa or its complex.