Time-resolved photoluminescence of ZnSe and ZnSe:Te single crystals

Abstract

This study examines the time-resolved photoluminescence spectra of zinc selenide (ZnSe) single crystals, both undoped and doped with the isovalent tellurium impurity, at 83 K, together with their steady-state photo luminescence spectra. The ZnSe crystals were excited using a nitrogen laser with a wavelength of 347 nm. In the steady-state photoluminescence spectra of undoped ZnSe, three emission bands were observed, with max ima at approximately 443, 458, and 610 nm. Time-resolved luminescence spectroscopy made it possible to resolve the 610 nm band into two components, with maxima near 580 and 640 nm. In the steady-state spectra of tellurium-doped ZnSe crystals, three emission bands were also detected, with maxima at approximately 450, 505, and 640 nm. Time-resolved photoluminescence spectra allowed the 505 nm band to be resolved in to two components, with maxima near 485 and 510 nm. The intensity of the red emission band at 640 nm in creases with increasing tellurium concentration. It is hypothesized that this red photoluminescence band is as sociated with an intracentric transition of an associative defect involving a zinc vacancy, an interstitial zinc atom, and a tellurium atom substituting for selenium. Considering the presence of an uncontrolled aluminium impurity in the crystals, an alternative interpretation is also possible: the 640 nm band may originate from an intracentric transition within a defect complex comprising a zinc vacancy, an aluminium atom substituting for zinc, and a tellurium atom substituting for selenium.