HIGH-QUALITY IN0.52AL0.48AS GROWN BY MODULATED ARSENIC MOLECULAR-BEAM EPITAXY

A modulated arsenic molecular beam epitaxy method has been developed for growing high quality In0.52Al0.48As under a condition compatible to the optimal growth condition of In0.53Ga0.47As without using a buffer layer or growth interruption. In this method, the As shutter is periodically opened and closed while the Al and In shutters are held constantly open. By adjusting the As shutter modulation rate, a layer-by-layer growth mode can be maintained throughout the growth as evident from the persistent strong reflection high-energy electron diffraction intensity oscillations. Without an In0.53Ga0.47As buffer layer, the unintentionally doped In0.52Al0.48As samples grown at 500 degrees C show very strong photoluminescence intensity and n-type conductivity with a background carrier concentration of similar to 5X10(15) cm(-3) and electron mobilities of 1900 and 3900 cm(2)/V s at 300 and 77 K, respectively. Very narrow 77 K photoluminescence spectra have been observed from In0.53Ga0.47As/In0.52Al0.48As quantum well stack structures grown by this new method.