ALLOY BROADENING IN PHOTOLUMINESCENCE SPECTRA OF CD1-XZNXTE CRYSTALS GROWN FROM TE SOLUTION

The excitonic line broadening of both donor and acceptor bound exciton s in bulk Cd1-xZnxTe crystal grown from Te solution has been investiga ted. The maximum linewidth of 3 meV for the neutral donor bound excito n (D0X) emission is for the first time determined and is in excellent agreement with the existing theory. On the other hand, the linewidth o f 10 meV for the acceptor bound exciton (A0X) in a highly alloyed samp le seems to be incompatible with the theory. With an increase in measu rement temperature, the A0X emission quenches much faster with larger red shift than the D0X emission. This observation indicates that the b inding energy of the exciton to the acceptor itself is distributed. In addition to the generally accepted alloy broadening mechanism (micros copic compositional fluctuation), this distribution is probably the ca use of the A0X line broadening.