THICK GAN EPITAXIAL-GROWTH WITH LOW DISLOCATION DENSITY BY HYDRIDE VAPOR-PHASE EPITAXY

Thick GaN layers were sown by hydride vapor phase epitaxy (HVPE) with the aim of using these layers as a homoepitaxial substrate to improve device quality of laser diodes or light emitting diodes. HVPE is very useful for thick layer growth since the growth rate can reach from sev eral ten up to one hundred micron per hour, In this experiment, the gr owth began as selective growth through openings formed in a SiO2 mask. Facets consisting of {1 (1) over bar 01} planes were formed in the ea rly stage and a continuous film developed from the coalescence of thes e facets on the SiO2 mask. As a result, GaN layers with a dislocation density as low as 6 x 10(7) cm(-2) were grown on 2-inch-diameter sapph ire wafers. These GaN layers were crack-free and had mirror-like surfa ce.