An Oxygen Doped Nucleation Layer for the Growth of High Optical Quality GaN on Sapphire

Abstract

We present a new oxygen-doped AlN nucleation layer for the growth of high quality GaN on sapphire by metalorganic vapor phase epitaxy. We investigated in detail the influence of oxygen in the gas phase in a range from 0.5 to 10 ppm. Around 4 ppm we obtained very stable and reproducible process conditions. A further optimization of the nucleation thickness resulted in GaN layers showing smooth and featureless surfaces with excellent spectroscopic properties. The best values were 45 arcsec in XRD rocking curve of the (002) peak and 1.7 meV in low temperature photoluminescence (PL) of the donor bound exciton. No yellow luminescence even at room temperature could be detected. Because of the low FWHM in PL a lot of features near the bandgap of GaN could be resolved. We observed the donor and acceptor bound exciton as well as the free A, B and C exciton.

Process optimization for the effective reduction of threading dislocations in MOVPE grown GaN using in situ deposited masks

“…The layers were deposited on 2 in c-plane (0 0 0 1) epi-ready sapphire wafers using an oxygen doped AlN nucleation layer (NL) [16]. Further details about the NL deposition and the subsequent GaN growth are given elsewhere [17].…”

Characterisation of quaternary AlInGaN thick layers and quantum wells grown by MOVPE

“…Trimethylgallium (TMGa), triethylgallium (TEGa), trimethylindium (TMIn), trimethylaluminum (TMAl) and ammonia ðNH 3 Þ were used as precursors. The substrate was first heated to 1120 1C in a hydrogen ambient and then the temperature was reduced to grow the oxygen-doped AlN nucleation layer [8]. At 1120 1C, a high-quality 1 mm thick GaN layer was deposited on the buffer (90 00 in XRD-Rocking curve).…”

Optimization of nucleation and buffer layer growth for improved GaN quality

“…In this study we investigate the optimization of the growth conditions for an oxygen-doped AlN NL [22] enabling the stable growth of high-quality GaN in metalorganic vapor phase epitaxy (MOVPE). We studied the influence of oxygen during the nucleation as well as the impact of the reactor pressure and the V-III ratio on the parasitic reactions between group-III source and ammonia [23,24].…”