用MOCVD在r面蓝宝石衬底上生长的a面GaN的独特电学性质研究

Nonpolar （1120） a-plane GaN films have been grown by low-pressure metal-organic vapor deposition on r-plane （1102） sapphire substrate. The structural and electrical properties of the a-plane GaN films are investigated by high-resolution X-ray diffraction （HRXRD）, atomic force microscopy （AFM） and van der Pauw Hall measurement. It is found that the Hall voltage shows more anisotropy than that of the c-plane samples; furthermore, the mobility changes with the degree of the van der Pauw square diagonal to the c direction, which shows significant electrical anisotropy. Further research indicates that electron mobility is strongly influenced by edge dislocations.     

金属有机物化学气相淀积法生长的Si掺杂GaN薄膜的应力，结构与电学特性研究

The stresses, structural and electrical properties of n-type Si-doped GaN films grown by metaiorganic chemical vapor deposition （MOCVD） are systemically studied. It is suggested that the main stress relaxation is induced by bending dislocations in low doping samples. But for higher doping samples, as the Si doping concentration increases, the in-plane stresses in the grown films are quickly relaxed due to the rapid increase of the edge dislocation densities. Hall effect measurements reveal that the carrier mobility first increases rapidly and then decreases with increasing Si doping concentration. This phenomenon is attributed to the interaction between various scattering process. It is suggested that the dominant scattering process is defect scattering for low doping samples and ionized impurity scattering for high doping samples.