This paper finds that the two-dimensional electron gas density in high Al-content A1GaN/GaN heterostructures exhibits an obvious time-dependent degradation after the epitaxial growth. The degradation mechanism was inv...This paper finds that the two-dimensional electron gas density in high Al-content A1GaN/GaN heterostructures exhibits an obvious time-dependent degradation after the epitaxial growth. The degradation mechanism was investigated in depth using Hall effect measurements,high resolution x-ray diffraction,scanning electron microscopy,x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy.The results reveal that the formation of surface oxide is the main reason for the degradation,and the surface oxidation always occurs within the surface hexagonal defects for high Al-content AlGaN/GaN heterostructures.展开更多
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 in...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.展开更多
基金Project supported by the Major Program and State Key Program of National Natural Science of China (Grant Nos 60890191 and 60736033)the National Key Science & Technology Special Project (Grant No 2008ZX 01002)
文摘This paper finds that the two-dimensional electron gas density in high Al-content A1GaN/GaN heterostructures exhibits an obvious time-dependent degradation after the epitaxial growth. The degradation mechanism was investigated in depth using Hall effect measurements,high resolution x-ray diffraction,scanning electron microscopy,x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy.The results reveal that the formation of surface oxide is the main reason for the degradation,and the surface oxidation always occurs within the surface hexagonal defects for high Al-content AlGaN/GaN heterostructures.
基金supported by the Major Program and Key Project of National Natural Science Foundation of China(Nos.60890191,60736033)the National Key S&T Special Project(No.2008ZX01002)
文摘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.
