TEMPERATURE-DEPENDENT EXCITON BEHAVIOR IN QUATERNARY GAINASSB ALGAASSB STRAINED SINGLE QUANTUM-WELLS/

We report the temperature-dependent exciton behavior in a quaternary G a0.67In0.33As0.01Sb0.99/Al0.25Ga0.75As0.02Sb0.98 strained single-quant um-well (SQW) structure by photoluminescence spectroscopy. Strong exci ton resonances are observed and have been attributed to localized exci tons below 80 K and to free excitons at high temperatures. Nevertheles s, we show that the experimental results of stronger exciton-phonon co upling in the quaternary SQW structure would lead to partial ionizatio n of free excitons at temperatures above 125 K, in good agreement with the line-shape analysis of the luminescence spectra which clearly sho ws the presence of band-to-band recombination. (C) 1996 American Insti tute of Physics.