Afm surface characterization in group III-V compound semiconductors

Structural, morphological and optical properties of AlN, GaN buffer materials and AlGaN/(AlN)/GaN heterostructures grown on sapphire substrate by MOCVD were investigated. XRD, AFM and PL techniques were used for characterization of the samples. The effects of AlN buffer layer on the sapphire substrate and AlN interlayer grown between GaN tampon-AlGaN barrier layers have been examined on the heterostructures. It was seen that AlN buffer layer improves the crystal quality and surface properties of heterostructures. Further improvement was achieved by inserting an AlN interlayer between GaN buffer and AlGaN barrier layers in the heterostructures. However, it was found that AlN interlayer leads to relatively rough interface in the heterostructures. In addition, it was seen that AlN interlayer changes the strain in the AlGaN barrier layer from tensile to compressive type.