Anisotropic mosaicity and lattice-plane twisting of an m-plane GaN homoepitaxial layer

Abstract

We have observed anisotropic mosaicity of an m-plane GaN homoepitaxial layer by X-ray diffraction topography imaging over a wafer and X-ray rocking curves measured at various wafer points.

Broadband Achromatic Quarter-Waveplate Using 2D Hybrid Copper Halide Single Crystals

“…This is often interpreted by calculating the combined retardation of N birefringent crystals with a thickness of d i and a birefringence value of n i as follows: R combined = ∑ i = 1 N n i λ d i . − In contrast, our A-QWP is based on an individual HCH single crystal without any heterostructure or multicomponent design. The HCH’s broadband retardation is possibly due to dislocation and distortion between the stacked inorganic layers, so-called out-of-plane mosaicity. , The HCH crystals used in the laser modulation measurement had a thickness of approximately 164 μm (Figure S9), and the distance between two copper chloride inorganic layers is estimated to be around 1.9 nm based on the lattice parameter determined from SCXRD. Out-of-plane dislocations and twists are anticipated to appear among the hundreds of copper chloride inorganic layers within the thick bulk HCH crystal with weak interlayer van der Waals interactions, leading to disordered stacked inorganic layers, as illustrated in Figure a.…”

Surface morphology smoothing of a 2 inch-diameter GaN homoepitaxial layer observed by X-ray diffraction topography

“…A lattice plane orientation mapping method that we developed using two azimuthal angles has enabled us to determine the lattice plane shape and full width at half maximum (FWHM) distribution statistically, and it is useful for evaluating the overall wafer quality in a short time. [18][19][20] The same imaging method has also been applied to a homoepitaxial layer. However, these topographic images are diffracted from the homoepitaxial layer or bulk substrate.…”