Recombination of charge carriers in neon cryocrystals containing oxygen impurity

The recombination of electrons and holes in neon crystals containing deep e lectron traps due to impurity oxygen along with weakly localized electron s tates of the matrix is investigated experimentally. Measurements are made b y the method of cathode-luminescence spectroscopy in VUV, UV, and visible w avelength ranges at temperatures varying from 2 to 8 K. It is found that th e temperature dependences of integral intensities of intrinsic and extrinsi c luminescence in solid solutions of oxygen in neon are similar and nonmono tonic by nature. The observed effect is analyzed in the model of two coexis ting channels of energy relaxation of electron excitations: through the Gam ma(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 te mperature range 6-8 K. Additional proofs are obtained for the possibility o f electron self-trapping in the Ne lattice with the formation of shallow lo calized states. (C) 1999 American Institute of Physics. [S1063-777X(99)0090 1-9].