Journal Article HVPE GaN wafers Mössbauer spectroscopy Research Support, Non-U.S. Gov't X-ray diffraction bunch-modes circular dichroism count-loss crystal growth diamond phase plate grazing incidence high-energy X-rays high-throughput devices hydride vapor-phase epitaxy films machine learning maximun count rates millisecond time-resolved experiments nanoXRD nuclear Bragg reflection nuclear monochromator photon-counting 2D detectors polarization analysis powder X-ray diffraction rate correction