科研之友
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摘要
InAlGaN/GaN heterostructures with various Al compositions have been grown on sapphire substrate using the metal organic chemical vapour deposition technique. The solid-to-gas phase ratio indicates a high Al incorporation efficiency. Atomic force microscopy reveals a smooth surface with the formation of hexagonal pits. The size and the density of the hexagonal pits increase with increasing Al mole fraction. The Hall effect and the capacitance-voltage (C-V) studies show the formation of a two-dimensional electron gas (2DEG) at the InAlGaN/GaN interface. A relatively higher Hall sheet carrier density compared with the 2DEG density estimated from the C-V profile indicates parallel conduction via the underlying GaN layer. It is observed that the 2DEG density decreases as a function of the Al composition and these results are discussed based on the increasing depth of the hexagonal pit and the background donor density.
- 出版日期2007-8-7
