Self-oriented growth of GaN films on molten gallium

This paper presents a concept of growing near single crystal quality GaN films over large areas through self-oriented growth of GaN platelets on molten gallium. The experiments were performed by nitridation of Ga films on amorphous quartz substrates using nitrogen plasma at low pressures of few mTorr. XRD texture analysis of the free standing GaN flakes with areas over 25 mm ² exhibited an overall c-axis tilt of 2.2°, while showing primary reflections from (0002) and (0004) planes. Further more, the cross-sectional TEM micrographs showed that the resulting GaN films are free from dislocation crops inside the grains but showed diffraction contrast due to small misorientation between the grains. The twist and tilt angles between adjacent columnar grains were determined using convergent beam electron diffraction technique to be less than 8° and 1°, respectively. HRTEM micrographs of the grain boundaries showed sharp interfaces with both twisted and perfect attachments.