Correlation between the sign of strain and the surface morphology and defect structure of InAlAs grown on vicinal (111)BInP

The MBE growth of InAlAs layers on vicinal (111)BInP substrates, misoriented by 1 degree toward [2 11], has been investigated. Scanning electron microscopy and atomic force microscopy revealed a dependence of InAlAs surface morphology on the layer's strain type; a strong trend to excessive surface step bunching characterized the compressively strained layers while much more regular surfaces, often with depressions, were observed on tensilly strained layers. However, high resolution X-ray diffraction suggested generally, a better crystalline structure for compressive layers and this was verified by transmission electron microscopy since twins and other defects appear to nucleate easily on tensile layers. Our results indicate the significant influence of the sign of strain in the strain relaxation-defect nucleation and adatom surface diffusion processes.