Identification of AsGa antisites in plastically deformed GaAs

Abstract

AsGa antisite defects formed during plastic deformation of GaAs are identified by electron paramagnetic resonance (EPR) measurements. From photo-EPR results it can be concluded that the two levels of this double donor are located near Ec −0.75 eV and Ev +0.5 eV. These values are coincident with the Fermi level pinning energies at Schottky barriers. The upper level can be related to the ’’main electron trap’’ EL2 in GaAs. Photoluminescence experiments before and after thermal annealing suggest that AsGa defects reduce the near band edge luminescence efficiency. A dislocation climb model is presented which is able to explain AsGa formation during dislocation movement. The production of AsGa antisites during dislocation motion under injection conditions in light emitting devices may thus be connected with degradation of the light output.

Defect studies in low-temperature-grown GaAs

“…At soooc the total PQ and NPQ absorption decreased sharply. Annealing of ASGa-related defects in L TMBE GaAs in this temperature range is very similar to that in irradiation damaged and plastically deformed GaAs (Haga, et al 1988, Weber, et al 1982. The fact that the annealing temperature is much lower than that for EL2 in LEC GaAs (11 00°C) has led to speculation that ASGa-related defects in LTMBE GaAs are different from EL2 ).…”

“…Electron paramagnetic resonance (EPA) has been the key experiment linking EL2 to the AsGa defect , Weber, et al 1982. For the singly ionized AsG a+ defect, the.…”

Electronic- and band-structure evolution in low-doped (Ga,Mn)As

“…21 During the growth a significant amount of about 1% excess arsenic is incorporated into the GaAs matrix, mainly in a form of arsenic antisites, As Ga , with a typical concentration of 1×10 20 cm -3 , which determine the electronic properties of LT-GaAs. 21,22 The As Ga defects act as double donors in GaAs giving rise to two deep energy levels in the band gap: the single donor level at E C -0.75 eV and the double donor level at E V + 0.52 eV, 23 where E C and E V are the conduction and valence band edges, respectively. When Mn is substitutionally introduced in the LT-GaAs host, the As Ga levels become depopulated resulting in compensation of the Mn Ga acceptors in very dilute (Ga,Mn)As layers.…”

EL2-related studies in irradiated and implanted GaAs

“…23 (1988) [1][2][3] -under a low-temperature photoexcitation it transforms into a different configuration, EL2 has been extensively studied for the past five years and its properties have been the subject of several recent review papers [4][5][6][7]. As a final result, this metastability which manifests by photoquenching behaviour of photocapacitance [3], photoconductivity [8], electron paramagnetic resonance (EPR) [9], photoluminescence and optical absorption [10,11] has become a kind of specific fingerprint for the presence of EL2.…”

“…Despite numerous experiments in many laboratories, its identity and structure have not been completely elucidated [7]. However, there is a large consensus associating the EL2 with the ASGA antisite defect [5,7] based mainly on stoechiometric correlations [6,12] and on EPR observations showing similar photoquenching behaviour of both EL2 and the AsGa EPR signal [9,13].…”