Temperature dependence of ZnO crystals from ion-beam-induced luminescence

Abstract

The effect of temperature (300-100 K) on the luminescence behavior of ZnO crystals irradiated with 2 MeV H+ were reported by ion-beam-induced luminescence (IBIL). Compared with constant-temperature IBIL spectra, the fluence mainly affects the luminous intensity, and the peak position shift is mainly affected by the temperature. For deep-band emissions (DBEs) at temperature ranges of 300–200 K, three emission bands exist in the red, orange-red, and green regions. These three emission bands illustrate different temperature dependencies with decreasing temperature: red and orange-red emission bands are not sensitive to temperature and redshift to green emission bands. The origins of three emission bands are the radiative recombination of deeply trapped holes with shallowly trapped electrons at the Oi, transition from the Zni to Oi level and transition related to oxygen vacancy levels. For DBE of 200–100 K, the orange-red emission band is not sensitive to temperature and has the same origin as the high-temperature section. The temperature dependence of UV band emission associated with recombination of excitons is caused by the temperature-induced band-gap shrinkage. The abnormal movement with temperature of violet emission band associated with Zni results from competition between localization effect at Zni and the band-gap shrinkage.