Growth of thin protective AlN layers on sapphire substrates at 1065 °C for hydride vapor phase epitaxy of AlN above 1300 °C

Abstract

A thin protective AlN layer was grown on a (0001) sapphire substrate at 1065 °C for main AlN layer growth at high temperature (> 1300 °C) by hydride vapor phase epitaxy (HVPE). The formation of surface pits on the surface of the epitaxial AlN layer, grown directly on the sapphire substrate at 1320 °C, could be prevented by growing the protective layer. The full‐width at half‐maximum (FWHM) of X‐ray diffraction (XRD) rocking curves of asymmetric (10 $\bar 1$ 0) and symmetric (0002) AlN decreased to 19.8 and 9.6 min, respectively. The concentration of oxygen impurities in the layer grown at 1320 °C was also reduced from 3 × 1019 to 4 × 1018 cm−3 by protecting sapphire substrate at 1065 °C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High-temperature growth of thick AlN layers on sapphire (0 0 0 1) substrates by solid source halide vapor-phase epitaxy

“…Also, the growth mode might be changed from three-dimensional (3D) to twodimensional (2D) mode during high-temperature growth. Several group reported the mode change from 3D to 2D by applying the change of V/III ratio, high growth temperature, or insertion of interlayer facilitates the bending of dislocations [13][14][15]. According to the reports of Gay et al [16] and Usui et al [17], we can roughly estimate the dislocation density of screw-and edge dislocations to be 1.1 Â10 7 and 1.9 Â 10 9 cm À2 , respectively.…”

“…3. Therefore, intermediate layer such as middletemperature AlN protective layer [15] is essential to obtain a highquality AlN layer at high temperatures.…”

Effects of AlN nucleation layers on the growth of AlN films using high temperature hydride vapor phase epitaxy

“…Several techniques for growing aluminum nitride layers on a variety of substrates have AlN deposition requires a high growth temperature above 1200 • C [14,17]. Nevertheless, thermal decomposition of c-plane sapphire starts to occur at 1200 • C [18] and AlN starts to decompose around 1400 • C [19] by reacting with hydrogen (H 2 ) used as a carrier gas, resulting in the formation of surface pits and in the degradation of AlN layer quality [20].…”

Preparation of a crack-free AlN template layer on sapphire substrate by hydride vapor-phase epitaxy at 1450°C

“…Therefore, HVPE of a thick AlN layer on a foreign substrate is one of the promising approaches for preparation of a freestanding AlN substrate or an AlN template [9][10][11][12][13] because of its high growth rate and scalability for large area growth. Our group has recently succeeded in using HVPE for growing AlN layers on a sapphire substrate above 1200 1C by growing a thin protective AlN layer at 1065 1C to suppress surface decomposition of the sapphire substrate [13]. However, the crystalline quality of the AlN layers was unsatisfactory, and cracking of the AlN layer with thickness of several tens of micrometers on sapphire substrate became another problem.…”