a ‐plane AlN and AlGaN growth on r ‐plane sapphire by MOVPE

Abstract

The growth of a‐plane (11‐20) AlN and AlGaN on r‐plane (1‐102) sapphire has been investigated with the aim of application to LEDs and LDs in the deep ultra‐violet region. a‐plane AlN and AlGaN were grown on r‐plane sapphire by low‐pressure metalorganic vapor phase epitaxy (LP‐MOVPE). The crystalline quality and surface morphology of a‐plane AlN were optimized at a growth temperature of 1250 °C with the off‐angle of r‐plane sapphire between ‐1° and +1°, and a‐plane AlGaN grown on the AlN layer using ‐0.45°‐off r‐plane sapphire as a substrate exhibited high crystalline quality. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Growth of non-polar a-plane AlN on r-plane sapphire

“…The reduced defects imply that the enhanced adatom diffusion at high temperature is important for obtaining a smooth AlN film. According to the previous reports, 22,23) thermal decomposition of the r-plane sapphire became noticeable above 1250 °C. The improved surface morphology with increasing temperature demonstrates that the first AlN layer firmly protected the sapphire surface.…”

“…21) High-temperature growth, which can facilitate the adatom diffusion, caused the roughening of the sapphire substrate since the oxygen atom is easier to desorb at the non-polar= semi-polar surfaces. 22,23) Here, we report the two-step growth of a-plane AlN on r-plane sapphire. A thin AlN layer was first grown at lower temperature to protect the sapphire surface.…”

Effects of AlN buffer layer thickness on the crystallinity and surface morphology of 10-µm-thick a-plane AlN films grown on r-plane sapphire substrates

“…102Þ substrates. [8][9][10][11][12][13][14][15] Nevertheless, the crystal quality and surface roughness of 10-µm-thick a-plane AlN templates are still inferior to those of c-plane AlN films on c-plane sapphire (0001) substrates.…”

The stacking fault annihilation in a-plane AlN during high-temperature annealing

“…[14][15][16][17] Miyagawa et al optimized the epitaxial parameters and realized high-quality a-AlN on r-sapphire substrates with various off-angles. 15 The high crystalline quality a-AlN was grown at 1250 °C on the 0.45°-off r-plane sapphire substrate. The full width at half maximum (FWHM) of X-ray diffraction rocking curves (XRC) of (11−20) plane a-AlN along c/m-direction are about 900/1250 arcsec.…”

“…13 Many efforts have been made to improve the crystalline quality of the hetero-epitaxial a-AlN layer. [14][15][16][17] Miyagawa et al optimized the epitaxial parameters and realized high-quality a-AlN on r-sapphire substrates with various off-angles. 15 The high crystalline quality a-AlN was grown at 1250 °C on the 0.45°-off r-plane sapphire substrate.…”