Characterization of a GaN wafer and a homo-epitaxial layer by synchrotron X-ray topography techniques

摘要

We have investigated the crystal quality of the 2 and 4-inch GaN wafer and homo-epitaxial layer bymonochromatic X-ray diffraction topography. GaN (11-24) diffraction images at various incidentangles were obtained to determine the image of maximum intensity and full-width at half-maximum(FWHM). [1-3] In addition, we have investigated the local structures of a GaN substrate through anenergy-resolved white X-ray diffraction topography method. A section topography geometry wasimplemented at various sample positions for the purpose of wafer mapping. The obtained images ateach position were piled up for the 3D matrix then sliced at a same energy position. The sliced imagesof the lower and higher diffraction energy showed periodic bottom-less and top-less featuresoriginated from the local lattice tilting, respectively.