Accommodation of Large Lattice Mismatch of GaP on GaAs(100) and GaAs on GaP(100) Layers Grown by MBE

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Abstract
To investigate the accommodation of a large lattice mismatch, the misfit strain of a GaP layer grown on a GaAs(100) substrate and a GaAs layer grown on a GaP(100) substrate were studied by X-ray diffraction and Raman spectroscopy as a function of the layer thickness. Epilayers were grown by MBE. The misfit strain began to relaxed at a thickness of 50 nm for GaP and 80 nm for GaAs. The magnitude of the saturated strain was 0.48% for GaP and 0.13% for GaAs. These magnitudes are insufficient to make a coherent interface. The tendency of our results are different from Matthews' prediction. His theory deals with layer-by-layer growth. Whereas the RHEED pattern showed an island formation during the initial stage of growth, subsequent islands coalesced to form a flat surface. Thus, the difference between the prediction and the experimental results was probably due to the difference in the growing mechanism.