HVPE homo-epitaxial growth of GaN on porous substrates

The results of experiments on homo-epitaxial growth by hydride vapor phase epitaxy (HVPE) of GaN films on free-standing porous substrates with closed surface porosity are presented. In the course of the studies, we observed a phenomenon of pore-dislocation reaction, which resulted in segmentation and pinning of dislocations within the porous layer in the substrate. This effect gives one an ability to control dislocation propagation on the level of collective effects, when interrelated processes take place, which involve the whole ensemble of structural defects, such as point defects (vacancies), linear defects (dislocations), and volume defects (vacancy associates and pores). As a result of the studies, threading dislocation density was reduced from 5 x 10(6) cm(-2) in the initial free-standing wafers down to 10(5) cm(-2) in the films grown on substrates with the nano-porous structure.