ALLOY-TRAPPED EXCITONS IN A NEW II-VI SEMICONDUCTOR SOLID-SOLUTION HG1-XZNXTE

Luminescence and reflectivity experiments were performed on Zn-rich Hg//1// minus //xZn//xTe crystals grown by THM. For compositions x greater than 0. 90, the low temperature luminescence spectra are dominated by a broad line I//L//1 located a few meV below the free exciton ground state deduced from reflectivity. Selective excitation of luminescence within the I//L//1 band on an x equals 0. 94 sample shows a narrowing line effect in the LO phonon luminescence replica. The behaviour of this line as a function of excitation energy and temperature indicates that it is due to radiative recombination of excitons localized in the potential wells associated with composition fluctuations. On samples richer in mercury (x less than 0. 90) the luminescence spectra become dominated by a deeper band I//L//2 we attribute to excitons trapped on non-identified defects.