Fabrication of free-standing GaN by using thermal decomposition of GaN

●Free-standing GaN fabricated by HVPE using an in-situ self-separation technique.●Thick GaN grown on sapphire was self-separated by using decomposable buffer layer and cap layer.●The FS-GaN revealed negligible residual stress and narrow (0002) omega rocking curve linewidth.●These results indicated the feasibility of the self-separated method for high quality FS-GaN wafer.

Free-standing GaN wafers were fabricated by hydride vapor phase epitaxy (HVPE) using an in-situ self-separation technique. Separation of GaN happened during the high-temperature GaN growth through thermal decomposition of the decomposable buffer layer (DBL). We optimized the growth condition of DBL, which affects not only the separation property but also the crystallinity of GaN. Free standing GaN revealed negligible residual stress, narrow (0002) omega rocking curve linewidth (67ʺ), and low etch pit density (6×106 cm−2) as well. The carrier concentration of 4×1018 cm−3 and mobility of 150 cm2/V s was observed from Hall effect measurement. These results showed the feasibility of the in-situ self-separation method to obtain high quality free-standing GaN wafer.