Semi-insulating GaN Grown on AlN Buffer/sapphire Substrate

A study of Semi-insulating GaN Grown on AlN buffer/sapphire Substrate by Metalorganic Chemical Vapor Deposition

We report the remarkably improved crystal quality of semi-insulating GaN grown by metalorganic chemical vapor deposition on an
AlN buffer layer, which is deposited on sapphire substrate. The electrical and structural properties are characterized by dark
current–voltage transmission line model and X-ray diffraction measurements. It is found that the crystal quality of the GaN epilayer is
strongly related with the growth temperature of the decreased-temperature GaN interlayer. In comparison with the normal GaN grown
on sapphire, the crystal quality is remarkably improved along with a semi-insulating electrical character. The high-mobility field effect
transistors device based on the semi-insulating GaN shows good pinch off properties. Our electrical measurement results of GaN grown
directly on an AlN buffer indicated that the as-grown-undoped GaN is naturally semi-insulating material. The origination of the residual
donors in normal GaN grown on sapphire substrate is also discussed.

Source:Science direct

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