Injection-level dependence, frequency response, and thermal quenching of the 1.39-eV luminescence in Sn-doped LPE GaAs

We have investigated the injection-level dependence, frequency response, and thermal-quenching characteristics of the extrinsic 1.39-eV bands in Sn-doped LPE GaAs. In lightly doped material, both the peak energy and band shape are insensitive to injection level. Frequency-response measurements show that the dynamic response of the 1.39-eV band is slow, with characteristic times of μsec. Thermal-quenching data show a relatively large activation energy which rules out the participation of normal shallow levels in the luminescence. In heavily doped material, the 1.39-eV band is very similar in shape to that in the lightly doped material. However, the band in heavily doped material shows an anomalous injection-level dependence and a lower thermal-quenching activation energy than the band in lightly doped material. Our data indicate that normal donor-acceptor pair transitions are not involved in the 1.39-eV luminescence; rather, the 1.39-eV luminescence results either from intracenter transitions in compact complexes or from partially forbidden transitions between the conduction band and a deep acceptor level associated with a complex.