Metastability of InGaAs/GaAs probed by in situ optical stress sensor

Real-time observations of film stress are presented from three growths of s trained InGaAs/GaAs layers. The initial metastable growth regime is analyze d to extract the alloy compositions of x = 0.136, 0.155. and 0.180. The str ain values at the end of the growths (thicknesses 0.791, 1.08, and 0.115 mu m, respectively) are then used to deduce the amounts of relaxation gamma = 0.808, 0.857, and 0.261, respectively. These data obtained from the in situ optical stress sensor are compared with conventional measurements using as ymmetric x-ray diffraction. The agreement is good, within 4%-6% for composi tion, indicating that the in situ sensor is suitable for quantitative study of strain relaxation during film growth. (C) 2001 American Vacuum Society.