Anomalous Edge Emission from Zinc Selenide Heavily Doped with Oxygen

Temperature behaviour of the photoluminescence spectra of polycrystalline ZnSe films with different surface treatment

“…[9,18,19] have associated the peak located at 458 nm with the radiation occurring during recombination of free electrons with holes bound at acceptors. The peak at λ max =464 nm can be attributed to recombination of electrons bound at shallow donors with holes bound at acceptors [18][19][20]. According to the spectral position of the main zero-phonon line of edge luminescence, the depth of the acceptor levels participating in such a donor-acceptor pair should be 0.12 eV less than the bandgap.…”

“…Moreover, the character of the PL spectrum described above is confirmed by a donoracceptor mechanism for the edge luminescence. The narrow line observed at the wavelength λ max =477 nm has been considered [19] as an anomalous edge luminescence, which appears due to selenium excess and strong doping of sample with oxygen. In our case, one can speak of a background impurity.…”

“…Many authors (see Refs. [8,10,19,21,24]) consider this band as a result of defectimpurity luminescence. They associate it with the occurrence of uncontrolled oxygen and copper impurities (i.e., background impurities), which are available in the crystalline lattice of CVD ZnSe.…”

“…The green band located at λ max =561 nm is, most likely, associated with the PL of impurity-defective complexes. These can be the complexes of intrinsic point defects (Zn i , V Zn ) with oxygen and copper [8,10,19,21,24]. Depending on the distance between the elements of these complexes, they can have slightly different modifications, and this changes the energy levels.…”

“…The authors of a number of works [10,19,21,24,[28][29][30] argue that the 'green' band observed in the region 508-550 nm is related to stoichiometric composition of CVD ZnSe, dissolved oxygen О Se and a presence of copper. If oxygen and copper are present as background impurities (≤ 10 16 cm -3 ), the short-wavelength bands located at 508-510 nm (at 80 K) are observed in the test samples.…”