Growth and Properties of GaN by Vapor Transport Epitaxy

Abstract

Highly c-axis oriented poly-crystalline GaN with a dimension of <TEX>$1{\sim}3\;{\mu}m$</TEX> was deposited on <TEX>$c-Al_2O_3$</TEX> substrate by vapor transport epitaxy (VTE) method at the temperature range of <TEX>$900{\sim}1150^{\circ}C$</TEX>. XRD intensities from (00'2) plane of grown GaNs were increased with reaction conditions which indicate the improvement of the crystal quality. In the PL spectra measured at 10 K, the spectrum composed with the neutral-donor bound exciton-related emission at 3.47 eV, crystal defect-related emission band at 3.42 eV and with its phonon replicas. The fact that intensity of <TEX>$I_2$</TEX> were increased and FWHM were decreased with growth conditions means that the quality of GaN crystals were improved. With this simple VTE technology, we confirm that the GaNs were simply deposited on sapphire substrate and crystal quality related to optical properties of GaN grown by VTE were relatively good. PL emission without deep level emission in spite of polycrystalline structure can be applicable to the fabrication of large area and low cost optical devices using poly-GaN grown by VTE.