Abstract
A modulated arsenic molecular beam epitaxy method has been developed for growing high quality In 0.52 Al 0.48 As under a condition compatible to the optimal growth condition of In 0.53 Ga 0.47 As 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 In 0.53 Ga 0.47 As buffer layer, the unintentionally doped In 0.52 Al 0.48 As samples grown at 500°C show very strong photoluminescence intensity and n-type conductivity with a background carrier concentration of ∼5×10 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 In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As quantum well stack structures grown by this new method.