Influence of substrate temperature on the mobility of modulation-doped AlxGa1−xAs/GaAs heterostructures grown by molecular beam epitaxy

Abstract

Single‐period modulation‐doped Al_0.3 Ga_0.7 As/GaAs heterostructures were grown by molecular beam epitaxy in a substrate temperature range of 580–750 °C. Excellent surface morphologies were routinely obtained throughout the entire range of growth temperatures. Highest mobilities (in dark) obtained were 8000, 90 000, and 196 200 at 300, 78, and 10 K, respectively. In room light, these figures improved to 9000, 110 000, and 250 000 cm²/Vs. The sheet carrier concentration yielding the best electron mobility was about 8×10¹¹ cm⁻². While the mobilities did not depend on the substrate growth temperature between 600 and 675 °C, some degradation was observed above 675 and below 600 °C.