The effect of aluminum mole fraction on the surface microroughness and morphology of AlxGa1−xAs grown at low temperature by molecular beam epitaxy

Abstract

AlGaAs layers of varying mole fraction x grown by molecular beam epitaxy are analyzed using scanning force microscopy. This relatively new technique allows high resolution imaging and analysis of surface morphology and roughness of conductors as well as nonconductors. The surface roughness and morphology of AlGaAs grown at low temperature (580 °C) are analyzed as its mole fraction x is changed from 0 to 0.8. Over an area of 400 μm2, the average roughness increases by as much as 26 Å as the AlGaAs surface morphology changes to be highly irregular with increasingly finer grains at higher mole fractions. The results show that high arsenic partial pressure and low substrate temperature inhibit the surface mobility of the aluminum atoms resulting in degradation in surface roughness.