Structural and Optical Properties of Zinc Nitride Films Prepared by Pulsed Filtered Cathodic Vacuum Arc Deposition

Polycrystalline zinc nitride films are deposited on Coming 7059 glass substrates by pulsed filtered cathodic vacuum arc deposition （PFCVAD）. The crystallographic structure is studied by means of x-ray diffraction. These measurements show that all the films are crystallized in the cubic structure, in a preferred orientation along the （332） and （631） directions. Weak XRD signal shows small crystallites distributed in an amorphous tissue. A small improvement of crystallinity is observed with annealing. Optical parameters such as absorption, energy band gap, Urbach tail, extinction coefficients have been determined. The Urbach tail energy is decreased with annealing at 500℃ for one hour. Energy band gap values are found to be increased by annealing.     

Energy of a Polaron in a Wurtzite Nitride Finite Parabolic Quantum Well

The effects of electron-phonon interaction on energy levels of a polaron in a wurtzite nitride finite parabolic quantum well （PQW） are studied by using a modified Lee-Low-Pines variational method. The ground state, first excited state, and transition energy of the polaron in the GaN/Al0.3Ga0.7N wurtzite PQW are calculated by taking account of the influence of confined LO（TO）-like phonon modes and the half-spaee LO（TO）-like phonon modes and considering the anisotropy of all kinds of phonon modes. The numerical results are given and discussed. The results show that the electron-phonon interaction strongly affects the energy levels of the polaron, and the contributions from phonons to the energy of a polaron in a wurtzite nitride PQW are greater than that in an A1GaAs PQW. This indicates that ehe electron-phonon interaction in a wurtzite nitride PQW is not negligible.     

Ⅲ族氮化物异质结构二维电子气研究进展

本文总结了近年来Ⅲ族氮化物半导体异质结构二维电子气的研究进展。从Ⅲ族氮化物材料晶格结构和特有的极化性质出发,重点讨论了AlGaN/GaN异质结构中二维电子气的性质,总结分析了异质结构中Al组分、势垒层厚度、应变弛豫度、掺杂等对二维电子气浓度和迁移率的影响,同时还涉及AlGaN/GaN/AlGaN,AlGaN/AlN/GaN和AlGaN/InGaN/GaN等异质结构二维电子气性质。     

Influence of Thickness of Field Emission Characteristics of Nanometre Boron Nitride Thin Films

Nanometre boron nitride (BN) thin films with various thickness (54-135nm) were prepared on Si(100) by rf magnetic sputtering physical vapour deposition. The field emission characteristics of the BN thin films were measured in an ultrahigh vacuum system. A threshold electric field of 11V/μm and the highest emission current density of 240μA/cm^2 at an electric field of 23V/μm were obtained for the about 54-nm-thick BN film. The threshold electric field increases with increasing the thickness in the nanometre range. The Fowler-Nordheim plots show that electrons were emitted from BN to vacuum by tunnelling through the potential barrier at the surface of BN thin films.     

金属有机化学气相沉积外延技术生长GaN基半导体发光二极管和激光二极管(Ⅰ)

文章评论性地介绍了金属有机化学气相外延技术（MOCVD）生长氮化物半导体GaN和InGaN以及激子局域化效应、量子束缚斯塔克效应对它们的光学性能的影响，详细比较了这两种效应对GaN基半导体发光二极管和激光二极管特性的影响，特别是量子束缚斯塔克效应以显著不同的方式影响着发光二极管和激光二极管的性能；文章还讨论了在A面蓝宝石衬底上生长GaN的情况．     

氮化物陶瓷颗粒增强铜基复合材料的干摩擦磨损性能研究

采用粉末冶金工艺制备了纯铜以及AlNp／Cu和TiNp／Cu系列铜基复合材料，研究了2种复合材料在不同颗粒含量、不同载荷及滑动速度等条件下与45^#钢对摩时的干摩擦磨损性能，用扫描电子显微镜观察其磨损表面形貌，用能谱仪分析了磨损表面的元素组成．结果表明：与纯铜相比，AlNpCu及TiNp／Cu复合材料的耐磨性能显著提高，随着氮化物颗粒含量增加，2种复合材料的磨损率先下降而后趋于稳定；载荷与滑动速度提高引起的热效应使得纯铜及其复合材料的磨损率增高；由于TiNp的硬度高于AlNp以及本身具有一定的自润滑性能，使得TiNp／Cu复合材料的耐磨减摩性能优于AlNp／Cu复合材料．     

Magnetic Properties of Melted ThMn12-Type Carbides and Their Nitrides

The carbides of NdDy0.2Fe12-yMoyC0.6 （y = 1.5, 2） crystallized in the ThMn12-type structure have been successfully synthesized by arc melting method, followed by a heat treatment. The magnetic properties are strongly enhanced with the addition of carbon. Upon the carbonation the saturation magnetization Ms is increased by about 20emu/g and the Curie temperature Tc is enhanced by 40-70K. The spin reorientation （SR） temperature decreases from 125 K for NdDy0.2Fe10Mo2 to 55 K for NdDy0.2Fe10MO2C0.6 indicating the change of magnetocrystalline anisotropy in the Nd sublattice. It is found that the intrinsic magnetic properties of the carbides can be improved by further nitrogenation, The composite carbon-nitrogen compounds show a Tc - 560K, M8 - 105 emu/g and Ha （anisotropy field） - 86kOe for NdDy0.2Fe10Mo2Co.6Nz and a Tc- 628K, M8 - 119 emu/g and Ha - 115kOe for NdDy0.2Fe10.5Mo1.5C0.6Nz. These magnetic properties are even better than those of simple nitrides, suggesting that these compounds can be considered as a good candidate for permanent magnet applications.     

Optimization and Finite Element Analysis of the Temperature Field in a Nitride MOCVD Reactor by Induction Heating

A susceptor structure with a ring channel for a vertical metalorganic chemical vapor deposition reactor by induction heating is proposed. Thus the directions of heat conduction are changed by the channel, and the channel makes the heat in the susceptor redistribute. The pattern of heat transfer in this susceptor is also analyzed. In addition, the location and size of the channel in the susceptor are optimized using the finite element method. A comparison between the optimized and the conventional susceptor shows that the optimized susceptor not only enhances the heating efficiency but also the uniformity of temperature distribution in the wafer, which contributes to improving the quality of the film growth.