Electroluminescence in narrow-gap semiconductors CdxHg1-xTe under interband breakdown in an electric field

Abstract

Within the framework of a simple two-band model, in the approximation of the method of effective parameters, the behavior of nonequilibrium carriers in solid solutions of the Cd x Hg 1-x Te (MCT) type in an external electric field is considered. The consideration is carried out for the range of values of the parameter x , in which the specified compound demonstrates the behavior of a narrow-gap semiconductor. Estimates show that for the real parameters of MCT samples in a wide range of variation of the value of x (and hence the width of the band gap) at an electric field exceeding some characteristic value of the interband breakdown field (depending on the parameter x and other physical parameters) in such systems, it is possible to obtain an inverse population distributions of carriers by energy. Moreover, the magnitude of the amplification factor at direct interband transitions can reach values up to 10 1 –10 2 cm −1 . The response of samples prepared from thick (not quantum-dimensional in terms of their thickness) MCT films to an external pulsed electric field is studied experimentally. The field was applied to the samples using ohmic contacts. The current-voltage characteristics of such samples and the dependences of the radiation intensity from the samples on the amplitude of the applied voltage pulses were obtained experimentally. The characteristic features of the responses obtained experimentally in these systems are discussed, as well as the possible prospects and difficulties for obtaining the laser effect using interband breakdown in an electric field. • Electroluminescence, narrow-gap semiconductors.