Abstract
In this work, the freestanding GaN single crystalline substrates without cracks were grown by hydride vapor phase epitaxy (HVPE). The GaN substrates, having a current maximum size of 350 $\mu\textrm{m}$-thickness and 10${\times}$10 $\textrm{mm}^2$ area, were obtained by HVPE growth GaN on sapphire substrate and subsequent mechanical removal of the sapphire substrate. A lattice constant of c$\_$0/=5.18486 ${\AA}$ and a FWHM of DCXRD was 650 arcsec for the single crystalline freestanding GaN substrate. The low temperature PL spectrum consist of excitonic emission and deep donor to acceptor pair recombination at 1.8 eV. The Raman E$_2$ (high) mode frequency was 567 cm$\^$-1/ which was the same as that of strain free bulk single crystals. The Hall mobility and carrier concentration was 283 $\textrm{cm}^2$/V$.$sec and 1.1${\times}$10$\^$18/ cm$\^$-3/, respectively. The freestanding and crack-free GaN single crystalline substrate suitable for the homoepitaxial growth of GaN, and the HVPE method are promising approaches for the preparation of large area, crack-free GaN substrates.
