GROWTH MODEL OF TEXTURED DIAMOND (111) FILM IN CH4/O2/H2 ATMOSPHERE

Partially oriented and highly textured diamond films on Si( 111 ) substrates were achieved by hot-filament chemical vapor deposition(HFCVD). High nucleation density greater than 5×10⁸cm^-2 was realiged in 3 min by near-surface glow discharge. The os-grown films were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Raman spectroscopy. It was found that by adding a small amount of oxygen to the mixture of CH₄/H₂, the appearance of facet(111) was well controlled, and the secondary nucleation on the facet(111) was suppressed greatly. Growth feature of homoepitaxy on diamond (111) surface was demonstrated to be in Stranski-Krastanov model by SEM.     

基于发光机理提高掺铒硅基材料发光效率的几条途径

掺铒硅基发光材料可以用于制备光通信用光源、光纤放大器，更重要的是可能成为实现硅基光电子集成技术的重要途径，已成为研究的热点之一．文章讨论了掺铒硅及掺铒硅基材料的发光机理，指出了制约实用化方面存在的问题．从不同方面着重探讨了共掺氧对提高掺铒硅发光效率的作用．最后介绍了基于掺铒硅发光机理提高掺铒硅基材料发光效率的几种途径、目前存在的主要问题及研究进展．     

CaO-SiO2绿光玻璃陶瓷荧光体的沉积组织结构对发光性质的影响

采用半熔化-淬冷的一步法制备了一种新型的硅酸钙绿光玻璃陶瓷,通过变化在1 550℃的保温时间,研究了玻璃陶瓷中沉积的微观结构对发光性质的影响.延长保温时间,玻璃陶瓷中沉积的发光晶体β-Ca SiO4:Eu2+和发光玻璃相的比例趋于减少,导致样品发射光谱红移,透明度增加.本论文同时分析了SiO2晶粒在玻璃基体中的沉积现象...     

Color-converted remote phosphor prototype of a multiwavelength excitable borosilicate glass for white light-emitting diodes

We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm-peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400-700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic "remote-phosphor" color conversion.     

Dominance of Antinodal Quasiparticles on the Transport Properties of Heavily Overdoped High-Tc Cuprates： Infrared-Reflectance Spectra

The infrared reflectance spectrum up to 2500cm^-1 for heavily overdoped T1-2201 at 300 K has been analysed under the semiclassical approximation. In this approach, we use two independent sets of parameters to fit the reflectance： the momentum-dependent Fermi velocity vk and the momentum-dependent scattering rate τ^-1 （εk ）. Unlike the case at optimal doping in which the transport properties are dominated by the nodal quasi-particles （QPs）, both the lifetime and the Fermi velocity of the QPs in the antinodal region near the Fermi surface increase remarkably for the heavily overdoped samples. Our fitting results indicate that the antinodal QPs tend to dominate the transport properties in heavily overdoped high-Tc cuprates.     

PHOTOLUMINESCENCE OF NANOCRYSTALLINE SiC FILMS PREPARED BY RF MAGNETRON SPUTTERING

Amorphous SiC films are deposited on Si (111) substrates by rf magnetron sputtering and then annealed at 1200℃ for different times by a dc self-heating method in a vacuum annealing system. The crystallization of the amorphous SiC is determined by Raman scattering at room temperature and X-ray diffraction. The experimental result indicates that the SiC nanocrystals have formed in the films. The topography of the as-annealed films is characterized by atomic force microscopy. Measurements of photoluminescence of the as-annealed films show blue or violet light emission from the nanocrystalline SiC films and photoluminescence peak shifts to short wavelength side as the annealing time decreases.