Kuok?tis, E.E.Kuok?tisKaraliunas, M.M.KaraliunasJur?enas, S.S.Jur?enasMiasojedovas, S.S.MiasojedovasSerevi?ius, T.T.Serevi?iusTing, S.-Y.S.-Y.TingHuang, J.-J.J.-J.HuangCHIH-CHUNG YANG2018-09-102018-09-10200918626351http://www.scopus.com/inward/record.url?eid=2-s2.0-77955453840&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/348162https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955453840&doi=10.1002%2fpssc.200982570&partnerID=40&md5=b7be8caf9832fecdd96395373e517dabPhotoluminescence (PL) and optical gain properties of ZnO and MgZnO epitaxial layers were investigated under different excitation conditions in a wide temperature range. The high-quality layers were grown by molecular beam epitaxy technique. CW laser radiation, nano- and pico-second light pulses were used as photoexcitation source. Spontaneous, stimulated, time-resolved and time-integrated PL of ZnO-based layers are analyzed. The PL of the layers under low excitation is caused by annihilation of free excitons in the near-band-edge region. Increase of excitation in ZnO leads to radiative recombination due to non-elastic collisions of excitons with typical P-line in the spectrum. Under extremely high levels of pumping excitons undergo the Mott transition and broad electron-hole band predominates in the PL spectrum. The latter mechanism is responsible for optical gain of ZnO. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.CW-laser; Elastic collision; Electron hole; Excitation conditions; Free excitons; High quality; Latter mechanism; Light pulse; Mott transitions; Near band edge; Optical gain properties; PL spectra; Radiative recombination; Temperature range; Time-resolved; ZnO; Building materials; Crystal growth; Excitons; Insulating materials; Molecular beam epitaxy; Molecular beams; Optical gain; Photoexcitation; Photoluminescence; Pulsed laser applications; Zinc oxideconference paper10.1002/pssc.2009825702-s2.0-77955453840