On the origin of the 1-eV band in photoluminescence from Cd1−x Zn x Te

Photoluminescence (PL) at 77 K from Cd1−xZnxTe samples (x = 0, 0.005 and 0.01) annealed at 900°C and cadmium vapor pressure PCd = 3 × 104−2 × 105 Pa has been studied. It was found that the contribution of the 1-eV band to the spectrum-integrated PL from these samples is independent of PCd, in contrast to Cd0.95Zn0.05Te samples in which this contribution increases up to ∼90% as PCd grows. The band is not shifted to shorter wavelengths as x becomes larger. The conclusion that Zn vacancies are involved in the formation of Cd1−xZnxTe properties is confirmed. The 1-eV band is attributed to capture of free holes to acceptor levels related to vacancies of both cadmium and zinc. These levels are closely spaced and, therefore, are difficult to resolve.