Recombination of charge carriers in neon cryocrystals containing oxygen impurity

Abstract

The recombination of electrons and holes in neon crystals containing deep electron traps due to impurity oxygen along with weakly localized electron states of the matrix is investigated experimentally. Measurements are made by the method of cathode-luminescence spectroscopy in VUV, UV, and visible wavelength ranges at temperatures varying from 2 to 8 K. It is found that the temperature dependences of integral intensities of intrinsic and extrinsic luminescence in solid solutions of oxygen in neon are similar and nonmonotonic by nature. The observed effect is analyzed in the model of two coexisting channels of energy relaxation of electron excitations: through the Γ(1/2,3/2) exciton subsystem and through the recombination of self-trapped two-center holes and electrons. It is shown that temperature variations of integral parameters of luminescence are mainly due to peculiarities of the recombination channel whose efficiency is determined by the probability of electron localization in the matrix lattice in the low-temperature regions (2.5–5 K) and by the probability of trapping at impurity centers in the temperature range 6–8 K. Additional proofs are obtained for the possibility of electron self-trapping in the Ne lattice with the formation of shallow localized states.