Journal article

Molecular-beam epitaxy of gallium nitride on (0001) sapphire substrates using ammonia

Ammonia is used for growing undoped GaN layers by gas source molecular-beam epitaxy on c-plane sapphire substrates. The growth mode is layer by layer as shown by the observation of reflection high-energy electron diffraction intensity oscillations. The structural quality is studied by x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Low-temperature photoluminescence (PL) and reflectivity demonstrate intrinsic excitonic emission. Room-temperature PL exhibits a strong band-edge intensity and a weak deep-level emission, the so-called yellow band. Finally, secondary ion mass spectroscopy is carried out to check the residual impurity levels of Si, C, and O. (C) 1998 American Institute of Physics. [S0021-8979(98)01203-1].


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