Deposition of carbon nitride films for space application

Carbon nitride thin films were prepared by electron-beam evaporation assisted with nitrogen ion bombardment and TiN/CN_x composite films were by unbalanced dc magnetron sputtering, respectively. It was found that the sputtered films were better than the evaporated films in hardness and adhesion. The experiments of atomic oxygen action, cold welding, friction and wearing were emphasized, and the results proved that the sputtered TiN/CN_x composite films were suitable for space application.     

Lattice structures and electronic properties of WZ-CuInS_2/WZ-CdS interface from first-principles calculations

Using the first-principles plane-wave calculations within density functional theory, the perfect bi-layer and monolayer terminated WZ-CIS(100)/WZ-Cd S(100) interfaces are investigated. After relaxation the atomic positions and the bond lengths change slightly on the two interfaces. The WZ-CIS/WZ-Cd S interfaces can exist stably, when the interface bonding energies are-0.481 J/m~2(bi-layer terminated interface) and-0.677 J/m~2(monolayer terminated interface). Via analysis of the density of states, difference charge density and Bader charges, no interface state is found near the Fermi level.The stronger adhesion of the monolayer terminated interface is attributed to more electron transformations and orbital hybridizations, promoting stable interfacial bonds between atoms than those on a bi-layer terminated interface.     

Thin film design for advanced thermochromic smart radiator devices

This paper describes the research on the materials and design methods for advanced smart radiator devices (SRDs) on large-area flexible substrates utilized on spacecraft. The functional material is thermochromic vanadium dioxide. The coating design of SRD is similar to the design of broadband filter coatings in a mid-infrared region. The multilayer coatings have complex structures. Coating materials must be highly transparent in a required spectrum region and also mechanically robust enough to endure the influence from the rigorous environments of outer space. The number of layers must be very small, suitable for the deposition on large-area flexible substrates. All the coatings are designed initially based on optical calculation and practical experience, and then optimized by the TFCALC software. Several designs are described and compared with each other. The results show that the emittance variability of the designed SRDs is great than 400\%, more advanced than the reported ones.     

Lattice structures and electronic properties of CIGS/CdS interface:First-principles calculations

Using first-principles calculations within density functional theory, we study the atomic structures and electronic properties of the perfect and defective （2VCu＋ Incu） CulnGaSe2/CdS interfaces theoretically, especially the interface states. We find that the local lattice structure of （2VCu＋ InCu） interface is somewhat disorganized. By analyzing the local density of states projected on several atomic layers of the two interfaces models, we find that for the （2VCu＋InCu） interface the interface states near the Fermi level in CulnGaSe2 and CdS band gap regions are mainly composed of interracial Se-4p, Cu-3d and S-3p orbitals, while for the perfect interface there are no clear interface states in the CulnGaSe2 region but only some interface states which are mainly composed of S-3p orbitals in the valance band of CdS region.     

Phase equilibrium of Cd_(1-x)Zn_xS alloys studied by first-principles calculations and Monte Carlo simulations

The first-principles calculations based on density functional theory combined with cluster expansion techniques and Monte Carlo(MC) simulations were used to study the phase diagrams of both wurtzite(WZ) and zinc-blende(ZB)Cd_(1-x)Zn_xS alloys.All formation energies are positive for WZ and ZB Cd_(1-x)Zn_xS alloys,which means that the Cd_(1-x)Zn_xS alloys are unstable and have a tendency to phase separation.For WZ and ZB Cd_(1-x)Zn_xS alloys,the consolute temperatures are 655 K and 604 K,respectively,and they both have an asymmetric miscibility gap.We obtained the spatial distributions of Cd and Zn atoms in WZ and ZB Cd_(0.5)Zn_(0.5)S alloys at different temperatures by MC simulations.We found that both WZ and ZB phases of Cd_(0.5)Zn_(0.5)S alloy exhibit phase segregation of Cd and Zn atoms at low temperature,which is consistent with the phase diagrams.     

ECR-PECVD制备n型微晶硅薄膜的研究

用电子回旋共振等离子体增强化学气相沉积(ECR-PECVD)的方法制备了磷掺杂微晶硅薄膜材料.通过Hall,Raman光谱和XRD的测试分析,研究了衬底温度和磷烷流量对掺杂薄膜组织结构和电学性能的影响.根据AFM照片分析了薄膜的表面形貌,进而推测了薄膜的内部组成.实验发现:衬底温度在250 ℃时,磷烷的加入会大大降低薄膜的晶化率.衬底温度提高到350 ℃后这种影响明显下降.薄膜的载流子浓度和电导率受薄膜晶化率影响明显,衬底温度的升高对薄膜电学性能提高有较大帮助.