Growth of β-Ga_2O_3 Films on Sapphire by Hydride Vapor Phase Epitaxy

Two-inch Ga_2O_3 films with（ˉ201）-orientation are grown on c-sapphire at 850–1050°C by hydride vapor phase epitaxy. High-resolution x-ray diffraction shows that pure β-Ga_2O_3 with a smooth surface has a higher crystal quality, and the Raman spectra reveal a very small residual strain in β-Ga_2O_3 grown by hydride vapor phase epitaxy compared with bulk single crystal. The optical transmittance is higher than 80% in the visible and near-UV regions, and the optical bandgap energy is calculated to be 4.9 e V.

Fabrication of GaN films through reactive reconstruction of magnetron sputtered ZnO/Ga_2O_3

A simple and easily operated technique was developed to fabricate GaN films. GaN films possessing hexagonal wurtzite structure were fabricated on Si(111) substrates with ZnO buffer layers through nitriding Ga2O3 films in the tube quartz furnace. ZnO buffer layers and Ga3O3 films were deposited on Si substrates in turn by using radio frequency magnetron sputtering system before the nitriding process. The structure and composition of GaN films were studied by X-ray diffraction, selected area electron diffraction and Fourier transform infrared spectrophotometer. The morphologies of GaN films were studied by scanning electron microscopy. The results show that ZnO buffer layer improves the crystalline quality and the surface morphology of the films relative to the films grown directly on silicon substrates. The measurement result of room-temperature photoluminescence spectrum indicates that the photoluminescence peaks locate at 365 nm and 422 nm.

扩镓Si基溅射Ga_2O_3氮化反应生长GaN薄膜

采用射频磁控溅射在扩镓硅基上溅射Ga2O3 氮化反应生长GaN薄膜。用X射线衍射 (XRD)、扫描电镜(SEM)、选区电子衍射 (SAED)、光电能谱 (XPS)和荧光光谱 (PL)对样品进行结构、形貌、组分和发光特性的分析。XRD、SAED和XPS分析证明 ,采用此方法得到六方纤锌矿结构的GaN多晶膜。SEM显示薄膜由均匀、结合紧密的纳米微晶粒组成 ,其直径约为50～100nm。PL发光谱显示位于344nm处 ,相对于365nm明显蓝移的带边峰 。

XPS Depth Profile Study of Sprayed Ga2O3 Thin Films

Ga2O3 thin films were fabricated by spray pyrolysis method using gallium acetylacetonate as source material and water as oxidizer. The films were annealed at 450°C for 60 minutes in argon atmosphere. X-ray photoelectron spectroscopy (XPS) depth profile studies were carried out to analyze the stoichiometry and composition of sprayed as-deposited and annealed Ga2O3 thin films. Surface layers and the inner layers of as-deposited and annealed films were found nearly stoichiometric.

椭球形α-Fe_2O_3纳米薄膜的制备与气敏性能

The α Fe 2 O 3 sol was prepared by a sol gel method from FeCl 3 ·6H 2 O. Thin nano particulate films of the α Fe 2 O 3 were deposited on glass substrate by dip coating sol gel technique. The structure and morphology of the thin films were characterized by XRD, UV Vis and AFM analysis methods. The XRD results revealed that the nano crystal with (104) preferential orientation has been formed on glass substrate. The UV Vis spectra showed that the nano particulate films obtained from Fe 2 O 3 aqueous colloidal sols are well transferred to glass substrate at dip coating rate of 80 mm/min. The α Fe 2 O 3 particles are ellipsoidal shaped, with particle size of about 5～7 nm. The multilayer films exhibited high sensitivity to ethanol vapor at room temperature.

Synthesis of GaN Nanorods with Herringbone Morphology

Hexagonal GaN nanorods are synthesized on quartz substrates through ammoniating Ga 2O 3 thin films deposited by radio frequency magnetron sputtering.X ray diffraction (XRD),scanning electron microscopy (SEM),high resolution transmission electron microscopy (HRTEM),and photoluminescence (PL) are used to analyze the synthesized GaN nanorods.Among the products,one dimensional GaN nanostructures owning protuberances on the surface are detected,which show interesting herringbone morphology.The analysis reveals that the herringbone GaN nanorods are polycrystalline composed of overlapping parallelepiped GaN nanocrystals arranged along the major axis.The large blue shift of yellow PL luminescence of the nanorods is observed at room temperature.

Synthesis of GaN nanorods on Si substrates with assistance of the vola-tilization of ZnO middle layers

GaN nanorods have successfully been synthesized on Si(111) substrates via ammoniating ZnO/Ga2O3 films at 950 degrees C. Ga2O3 thin films and ZnO middle layers were deposited in turn on Si(111) substrates by r.f. magnetron sputtering system. ZnO volatilized at 950 degrees C in the ammonia ambience and Ga2O3 reacted to NH3 to fabricate GaN nanorods in the later ammoniating process. The volatilization of ZnO layers played an important role in the fabrication. The structure and composition of the GaN nanorods were studied by X-ray diffraction (XRD) and Fourier transform infrared spectrophotometer (FTIR). The morphology of GaN nanorods was investigated using scanning electron microscopy (SEM) and transmission electronic microscope (TEM). The analyses of measured results revealed that GaN nanorods with hexagonal wurtzite structure were prepared by this method.

The structure and magnetic properties of β-(Ga_(0.96)Mn_(0.04))_2O_3 thin film

High quality epitaxial single phase（Ga_（0.96）Mn_（0.04））_2O_3 and Ga_2O_3 thin films have been prepared on sapphire substrates by using laser molecular b（eam）epitaxy（L-MBE）. X-ray diffraction results indicate that the thin films have the monoclinic structure with a 201 preferable orientation. Room temperature（RT） ferromagnetism appears and the magnetic properties of β-（Ga_（0.96）Mn_（0.04））_2O_3 thin film are enhanced compared with our previous works. Experiments as well as the first principle method are used to explain the role of Mn dopant on the structure and magnetic properties of the thin films. The ferromagnetic properties are explained based on the concentration of transition element and the defects in the thin films.