The .gan / Al <sub> 2 </ Sub> O <sub> 3 </ Sub> (0001) Lattice Mismatch Between The Epitaxial Growth Of Heterostructures Of Pamocvd

GaN, one of the third generation semiconductor materials, becomes the hot point of research because of its excellent characteristics. It has wide potential application and development in the fields of microelectronics and optoelectronics.This dissertation presents the investigation on the epitaxy growth with large lattice mismatch (14%) heterostructures GaN/Al2O3(0001), by an electron cyclotron resonance (ECR) plasma assisted metalorganic chemical vapor deposition (PAMOCVD) with a nitrogen plasma as a nitrogen source at low temperature (700℃) . In order to release the stresses originated from the lattice mismatch and reduce the defect densities, sapphire substrate surfaces are preprocessed by H-plasma cleaning , N-plasma nitriding and the low temperature buffer growth. The film crystal structure is characterized by XRD and the film surfaces morphology is observed by AFM. The Growth parameters were optimized and an ideal growth conditions have been got finally by comparing the results of RHEED. The result of XRD and AFM indicates that high quality GaN films were grown on sapphire. A better result is got when cleaning sapphire by hydrogen and nitrogen plasma. The mechanism of the 30?rotation of (0001) nitride plane produced by the nitridation with respect to the (0001)Al2O3 is discussed. We observed that zinc blende GaN epilayer can grow on the wurtzite GaN buffer at low temperature and give a logical explanation to it. Additionally, the real-time monitoring system of semiconductor film growth for the ESPD - U device is improved according to the characteristics of the growth procedure .