INTERFACE OPTIMIZATION OF GAINAS/GAINASP (LAMBDA = 1.3 MM) SUPERLATTICES BY THE USE OF GROWTH INTERRUPTIONS

We have studied the effect of growth interruptions on the optical and structural quality of 30 period GainAs/GaInAsP (l = 1.3 mum) superlattices grown by metal organic vapour phase epitaxy. A photoluminescence linewidth of 6.0 meV at 6 K and satellite reflections in X-ray diffraction up to the - 5th order were obtained, using a gas switching scheme, where the reactor was exposed to a mixture of PH3 and AsH3 for 0.5 s. The refractive indices of those samples, measured by ellipsometry, were in excellent agreement With theoretical values. For longer interruptions, the presence of PH3 was identified as the major cause for a significant degradation of the crystallographic and optical sample quality. Dynamical simulation of the X-ray diffraction patterns reveals a compositional inhomogeneity in the very first periods of the quantum well stack. The extension of this disturbed region was dependent on the applied growth interruption.