Lattice Parameters of GainP/GaAs Epi-Layers at Temperatures 77 to 752 K

Abstract

Three GaxInt–XP epi‐layers on GaAs substrates are examined with an X‐ray diffractometer at temperatures from 77 to 752 K. Lattice parameters in directions perpendicular and parallel to the surface are measured with the Bond method. In the sample of perpendicular misfit Δa⊥/a = 0.3% and thickness 3 μm a parallel misfit Δa|/a = 0.014% is spotted. Some information about the quality of samples is obtained with a double crystal arrangement of two (004) reflections. The thicknesses of samples are derived from the ratio of intensities of radiation diffracted from the layer and the substrate. The relaxed lattice constants are evaluated to obtain values of x and to confront them with photoluminescence measurements. The thermal expansion coefficients of relaxed Ga0.5 In0.5P layers vary from 2.7 × 10−6 K−1 at 92 to 137 K to 5.7 × 10−6K−1 at 712 to 752 K and of the GaAs substrate from 2.8 × 106 K−1 at 92 to 137 K to 6.9 × 10−6K−1 at 712 to 752 K.

Thermal Properties

“…[39] measured the a th value of relaxed Ga 0.5 In 0.5 P layers grown on GaAs by LPE and reported it as $4.6 Â 10 À6 K À1 . This value (open circle) agrees well with the linear interpolation scheme (solid line).The data inFigure 2.21(b) can be approximated by the linear interpolation scheme (solid line).…”