| Title |
Research Papers / Electronic , Magnetic & Optical Materials : Critical Layer Thickness and Refractive Index of InGaAs / GaAs Layer |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Abstract |
InGaAs layers with a thickness of 3㎛ are grown on undoped GaAs substrates which have [001] exact and 2°off toward [101] direction surfaces. The refractive indices of the samples with various crystallographic directions have been measured by means of variable azimuthal angle ellipsometry technique. InGaAs layers have shown twofold symmetric anisotropy with a maximum at [11￣1] and a minimum at [110] directions for 6328Å laser light. The Bragg angle difference ΔΘ and the full width at half maximum(FWHM) have also been measured by double crystal X-ray diffraction along [11￣0] and [11￣0] directions. The results indicate that the anisotropy of the refractive index as well as the FWHM are closely related to the direction of the misfit dislocation formed by the lattice mismatch between the InGaAs layers and the substrate. We introduce a simple formula which represents the critical layer thickness of InGaAa/GaAs single layer as a function of In contents from the geometric form of 60° type dislocation. The results agree well with the experimental measurements. |