{'fraction_non_alphanumeric': 0.01867704280155642, 'fraction_numerical': 0.004669260700389105, 'mean_word_length': 5.366336633663367, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Improved photoluminescent properties of ZnS: Mn due to the δ‐doping process

Abstract— An investigation on the growth of high‐quality homogeneously and delta‐doped ZnS: Mn layers by MBE is reported. Homogeneously doped ZnS: Mn films showed that the maximum luminance for the Mn emission occurred at a concentration of 3 mol% before luminescence concentration quenching was observed. The delta‐doping technique was used to concentrate the Mn centers in separate atomic layers in order to suppress three‐dimensional coupling between the Mn centers and traps responsible for the quenching. This doping technique was shown to quadruple the photoluminescence efficiency of the Mn centers compared to equivalently doped homogeneous material grown under the same conditions. From the dependence of the Mn emission intensity on the distance between doping planes, the optimum spacing was found to be 9–15 nm. Mn depth profiles determined by SIMS revealed broad Mn peaks with a FWHM of about 10 nm, indicating diffusion of Mn into the undoped ZnS region. Studies of the temperature dependence of the luminescence decay of both homogeneously and delta‐doped ZnS: Mn films indicated a different energy‐transfer mechanism for the delta‐doped films than that known for the homogeneously doped ones.