Masahiko Ogirima

Lattice mismatch at the interface in GaP-GaP and GaAIAs-GaAs epitaxial growth

Abstract The lattice mismatch at the epitaxial layer-substrate interface was studied by X-ray diffraction techniques for both GaP/GaP and GaAlAs/GaAs epitaxial growth from the liquid phase. A planar defect at the interface, whose fault vector is normal to the interface, was observed. This defect is due to a lattice mismatch between the epitaxial layer and the substrate, however the deformation of the unit cell in the epitaxial layer is such that the lattice expands or contracts normal to the substrate but the lattice spacing parallel to the substrate does not change. The volumes of the unit cells in the epitaxial and the substrate crystal are different due to the difference of nitrogen concentration (GaP/GaP) or heteroepitaxy (GaAlAs/GaAs). The origin of this lattice mismatch was also related to the growth conditions. It was found that the lattice mismatch occurred depending on the magnitude of the gradient of the lattice parameter in the epitaxial layer.

Effect of Donor Concentration on Several Properties of Gallium Arsenide Phosphide

The effects of donor concentration on electrical and electroluminescent properties in vapor-grown GaAs0.62P0.38 single crystals are investigated at 300 K. Electron mobility decreases rapidly for ND(donor concentration)> ~1017cm-3, and the obtained maximum electron mobility is 3150 cm2/V.s (ND=1.54×1015cm-3). It is revealed that heavily doped (ND≈1017cm-3) samples show a relatively strong infrared emission spectrum peaked at ~9500A and that this infrared emission causes different behaviors in I–ηext (the quantum efficiency) curves between the samples of low and high donor level.

Vapor-Phase Epitaxial Growth and Defects of Gallium Phosphide

Gallium phosphide single crystals are epitaxially grown on gallium arsenide substrates from vapor phase by an open-tube method. Surface morphology and crystal defects of growth layers are investigated in relation to growth conditions. It is found that the growth rate and the crystal perfection are much affected by the concentration of phosphorus trichloride in the carrier gas. Under the hillocks on the surface, there exist pyramidal imperfect regions. These defective regions are investigated by optical microscopy, polarization microscopy and X-ray topography.