In situ characterization by reflectance difference spectroscopy of III–V materials and heterojunctions grown by low pressure metal organic chemical vapour deposition

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The reflectance difference spectroscopy (RDS) technique has recently been used successfully to study the molecular beam epitaxial growth of GaAs and AlAs. An extension of such in situ characterization to the metal organic chemical vapour deposition (MOCVD) growth of III–V compounds would be very helpful, because electronic measurements such as reflection high energy electron diffraction are not possible in the MOCVD growth environment. In this paper preliminary results are reported of RDS studies performed in a low pressure MOCVD reactor under optimal growth conditions. The RDS signatures of GaInAsInP and GaAsGaInP heterojunctions and superlattices are presented for the first time. It is possible using the RDS technique to determine in situ the ⪡011⪢ and ⪡01 1⪢ directions of III–V compounds in a non-destructive way, which is very important for technological applications. A study of InAs growth suggests that one can have access to the III:V ratio on the surface using this technique. The occurrence of very large surface anisotropies (10% or more) related to the growth of lattice mismatched materials is reported.