Composition and refractive index of Ga1−<i>x</i>Al<i>x</i>As determined by ellipsometry

Abstract

The compositions of 42 thin Ga1−xAlxAs layers grown by liquid-phase epitaxy were measured by reflection ellipsometry. The refractive index n (x) was determined over the composition range x?0.61 at the wavelength λ=546.1 nm. The composition of the calibration samples was obtained from electron microprobe analysis. The 800 °C solidus isotherm of the Ga-Al-As phase diagram is determined and compared with existing phase diagrams. Furthermore, the thickness of the natural oxide layers on the samples was measured as a function of alloy composition and of time.