Large-Scale Defect Clusters with Hexagonal Honeycomb-like Arrangement in Ammonothermal GaN Crystals oleh Lutz Kirste, Thu Nhi Tran Thi Caliste, Jan L. Weyher, Julita Smalc-Koziorowska, Magdalena A. Zajac, Robert Kucharski, Tomasz Sochacki, Karolina Grabianska, Malgorzata Iwinska, Carsten Detlefs, Andreas N. Danilewsky, Michal Bockowski, José Baruchel