Carbon incorporation during growth of GaAs at low temperatures

Abstract

Heavily C-doped GaAs layers grown by solid-source molecular beam epitaxy at low substrate temperatures, 195°C< T G<375°C, are investigated using infrared absorption measurements. The heavy C-doping (about 2×10 19 cm −3) causes a compensation of the strain created by the simultaneously formed As antisite defects, As Ga. The contents of As Ga and substitutionally incorporated carbon, C As, are determined as a function of T G. Additionally, for T G<400°C the local vibrational mode absorption lines of four C-containing complexes are found. These lines, located at frequencies around 1800 cm −1, are most likely due to C–C stretching modes. For T G<250°C the C-complexes are responsible for the strain compensation, as no C As is detectable. After annealing at 600°C the content of C As is not changed, but the C-complexes completely disappear.