Dislocation reduction in GaN grown by hydride vapor phase epitaxy via growth interruption modulation

Thick GaN layers have been deposited on c-Al2O3 (0001) substrates using hydride vapor phase epitaxy by modulating the growth process via switching on/off GaN growth. Cathodoluminescence and transmission electron microscopy images of the cross-sectional structure show that there are separated multilayers structure in the GaN films. The dislocations density decreases from 1010 cm−2 in the initial layer to 109–108 cm−2 in the subsequently grown layer and then to 107 cm−2 in the top layer. This shows that the interruption of the growth process is helpful for suppression of structural defects. X-ray diffraction and photoluminescence measurements also demonstrate the high quality of the GaN films.