Technical Insight
Growth of Cubic GaN With Intermediate Buffer (Research Review)
Cubic GaN grown on GaAs substrates can be easily cleaved along the same planes as the substrate facets, a property that could lead to simplified device processing. However, suitable growth conditions, such as low V/III ratios and high growth temperatures, are essential. Since the GaAs substrate is not thermally stable, a GaN intermediate layer has been inserted between the low-temperature buffer layer and high-temperature GaN epilayer in order to achieve the growth of cubic GaN by MOVPE. The intermediate layer was grown by MOVPE at moderate temperatures of 850 C both to avoid thermal damage to the substrate and to provide a flat cubic template. This approach was successful and enabled the growth of cubic GaN on GaAs at higher temperatures. Even at a growth temperature of 980C, a smooth interface between the GaN layer and GaAs substrate was observed. Photoluminescence and X-ray diffraction measurements corroborated this, and revealed that the crystal quality of the cubic GaN layer was much improved compared to growth without the high temperature intermediate buffer. J. Wu et al, University of Tokyo, Japan J. Cryst. Growth, 2000, 221, p. 276
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