Microcharacterization of Conformal GaAs on Si Layers by Spatially Resolved Optical Techniques
The growth of III-V layers on Si substrates has the interest to combine the high performance of these semiconductors with the mature technology of Silicon. However, the large lattice mismatch and the difference in the thermal expansion coefficients prevent the obtention of layers free of crystal defects for minority carrier devices. Recently, a growth technique, the so-called conformal growth, allows the obtention of nearly defect free GaAs and AlGaAs layers on Si substrates. This method is basically a confined lateral growth. Layers of submicrometric thickness with very low defect concentration are obtained. We present herein a study of some GaAs conformal layers on Si. The layers are characterized by spatially resolved techniques as PhotoLuminescence Imaging (PLI), Cathodoluminescence (CL) and microRaman. Different properties of these layers are studied. In particular, the stress distribution, the existence of growth failures or the free carrier distribution in doped layers. Some others aspects as the influence of the seed orientation, the existence of nucleations and the crystalline order are also discussed.
KeywordsBright Band Large Lattice Mismatch Free Electron Density Longitudinal Optic Hydride Vapour Phase Epitaxy
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