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An InGaN multiple-quantum-well (MQW) violet-light-emitting diode (LED) is grown by low-pressure metalorganic chemical vapour deposition. It is found that photoluminescence wavelength of the InGaN MQW violet LED is lengthened with increasing growth temperature and with the increasing trimethylindium flow of the InGaN wells. The electroluminescence peak wavelength of the violet LED are about 401 nm with full width at half maximum of 14 nm, and the output power in injection current of 20 mA at room temperature is 4.1 mW.

The near-ultraviolet lighting-emitting-diodes (UV-LEDs) with the InGaN/GaN multi-quantum-well (MQW) structure were grown by low-pressure metalorganic vapour phase epitaxy. The double crystal x-ray diffraction revealed a distinct second-order satellite peak. The near-ultraviolet InGaN/GaN MQW LEDs have been successfully fabricated to emit at 401.2 nm with narrow FWHM of 14.3 nm and the forward voltage of 3.6 V at 20 mA injection current at room temperature. With increasing forward current from 10 mA to 50 mA, the redshift of the peak wavelength was observed due to the band-gap narrowing caused by heat generation.

The effects of dopants on the defects of GaN films were investigated by using different methods, such as wet, etching of pits, x-ray diffraction and photoluminescence (PL). Three kinds of the samples were prepared with different dopants, that is, nominally undoped, Si-doped and Mg-doped GaN films. It was found that the lowest density of the, etched pit was existed in the nominally undoped GaN, while the highest in the Mg-doped sample. The effects of the dopants on the, etching pits were discussed.

InAlN/GaN heterojunction structures are grown on two-inch c-face(0001) sapphire substrates by metalorganic chemical vapour deposition. AlN and AlGaN interlayers are intentionally inserted into the structure to improve the electrical properties. The lowest sheet resistance of 359Ω/sq and the highest room-temperature two-dimensional electron gas (2DEG) mobility of 1051 cm2 V−1s−1 is obtained in the structure with AlN thickness of 1.3 nm. The structure with AlN thickness of 2 nm exhibits the highest 2DEG concentration of 1.84 × 1013 cm−2. The sample with an AlGaN interlayer gives a smoother surface morphology compared to the one using an AlN interlayer, indicating potential applications of this technique in device fabrication.