Fabrication and Properties of Double-Side Tl2Ba2CaCu2O8 Thin Film on CeO2 Buffered Sapphire Substrate

The double-side Tl2Ba2 CaCu2O8 （Tl-2212） superconducting thin films were fabricated on CeO2 buffered sapphire substrates. The reactive magnetron sputtering technique was used to grow CeO2 buffer thin films on sapphire substrates. Making use of the metal cerium as a sputtering source, the depositing rate is much higher compared with the CeO2 target. The Ti-2212 thin films on CeO2 buffered sapphire substrates were fabricated by adc magnetron sputtering and post-annealing process. The x-ray diffraction indicates that the thin film is pure Tl-2212 phase with the e-axis perpendicular to the substrate surfaces, and epitaxially grown on the CeO2 buffered sapphire. The critical transition temperature Tc is around 106K, the critical current density Jc is around 3.5 MA/cm^2 at 77K, and the microwave surface resistance R8 at 77K and 10 CHz of the film is as low as 390μ Ω.     

Effect of Different Substrate Temperature on Sb-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition on Sapphire Substrates

Sb-doped ZnO thin films are deposited on c-plane sapphire substrates by pulsed laser deposition. Hall results indicate that the conductivity of the Sb-doped ZnO thin films is strongly dependent on the substrate temperature. The sample deposited at the temperature of 550°C exhibits p-type conductivity. It gives a resistivity of 15.25Ω＆#12539;cm, with a Hall mobility of 1.79cm2V-1s-1 and a carrier concentration of 2.290×1017cm-3 at room temperature. The x-ray diffraction indicates that the Sb-doped ZnO thin films deposited in the range of 450-650°C are high c-axis oriented. Low-temperature photoluminescence spectra indicate that the sample deposited at 550°C shows the strong acceptor-bound exciton （A0X） emission.     

Effect of Interface Nanotexture on Light Extraction of InGaN-Based Green Light Emitting Diodes

We report the enhancement of the light extraction of InGaN-based green light emitting diodes （LEDs） via the interface nanotexturing. The texture consists of high-density nanocraters on the surface of a sapphire substrate with an in situ etching. The width of nanocraters is about 0.5 μm and the depth is around 0.1 μm. It is demonstrated that the LEDs with interface texture exhibit about a 27% improvement in luminance intensity, compared with standard LEDs. High power InGaN-based green LEDs are obtained by using the interface nanotexture. An optical ray-tracing simulation is performed to investigate the effect of interface nanotexture on light extraction.     

气体湍流对泡生法生长蓝宝石单晶温场的影响

本文采用专业晶体生长模拟软件CrysVUn对泡生法生长大尺寸蓝宝石单晶进行了计算机模拟.分析了气体压力对泡生法生长蓝宝石单晶的温场、气体速度场的影响.结果发现在气压P≥105Pa时,特别是在引晶初期,容易出现籽晶根部熔化,这在实验中得到了很好的验证,并提出了三种解决方案.     

高温退火对蓝宝石基片的表面形貌和对CeO缓冲层以及Tl-2212超导薄膜长的影响

研究了蓝宝石(1102)基片在不同温度和时间下退火时表面形貌和表面相结构的变化,以及它对CeO2缓冲层和T1-2212超导薄膜生长的影响.原子力显微镜(AFM)研究表明,在流动氧环境中1000℃温度下退火,蓝宝石(1102)的表面首先局部区域形成台阶结构,然后表面形成叠层台阶结构,随着退火时间的延长.表面发生了台阶合并现象,表面形貌最终演化为稳定的具有光滑平台的宽台阶结构.XRD测试表明,通过高温热处理可以大幅度提高蓝宝石基片表面结构的完整性.在1000℃温度下热处理20 h的蓝宝石(1102)基片上可以生长出具有面内取向的CeO2(001)缓冲层.在具有缓冲层的蓝宝石基片上可以制作出高质量c轴织构的外延11-2212超导薄膜,其临界转变温度(Tc)为104.7 K,液氮温度下临界电流密度(Jc)达到3.5 MA/cm2,微波表面电阻R(77 K,10 GHz)约为390μΩ.     

Enhanced Photoluminescence of InGaN/GaN Green Light-Emitting Diodes Grown on Patterned Sapphire Substrate

Green InGaN/GaN based light-emitting diodes （LEDs） are fabricated both on planar and wet-etched patterned sapphire substrates by metalorganic vapour phase epitaxy （MOVPE）. Their photoluminescence （PL） properties of the two samples are studied. The results indicate that the PL integral intensity of the green LED on the patterned substrate is nearly two times of that on the planar one within the whole measured temperature range. The enhanced PL intensity in the green LED on the patterned substrate is shown completely contributed from the extraction efficiency, but not from the internal quantum efficiency. The conclusion is supported by temperature-dependent PL analysis on the two samples, and the mechanisms axe discussed.     

Generation of a Sub-10fs Laser Pulse by a Ring Oscillator with a High Repetition Rate

A compact femtosecond Ti：sapphire ring oscillator composed of chirped mirrors is designed. By accurately optimizing the intra-cavity dispersion and the mode locking range of the ring configuration, we generate laser pulses as short as 7.7fs with a repetition rate as high as 745 MHz. The spectrum spans from 660nm to 94Ohm and the average output power is 480mW under the cw pump laser of 7.5 W.     

Effect of Different Substrate Temperature on Phosphorus-Doped ZnO Thin Films Prepared by PLD on Sapphire Substrates

Phosphorus-doped ZnO （ZnO：P） thin films are deposited on a c-plane sapphire in oxygen at 350℃, 450℃, 550℃ and 650℃, respectively, by pulsed laser deposition （PLD）, then all the ZnO：P samples are annealed at 650℃ in oxygen with a pressure of 1 × 10^5 Pa. X-ray diffraction measurements indicate that the crystalline quality of the ZnO：P thin films is improved with the increasing substrate temperature from 350℃ to 550℃. With a further increase of the deposition temperature, the crystalline quality of the ZnO：P sample is degraded. The measurements of low-temperature photoluminescence spectra demonstrate that the samples deposited at the substrate temperatures of 350℃ and 450℃ show a strong acceptor-bound exciton （A^0X） emission. The electrical properties of ZnO：P films strongly depend on the deposition temperature. The ZnO：P samples deposited at 350℃ and 450℃ exhibit p-type conductivity. The p-type ZnO：P film deposited at 450℃ shows a resistivity of 1.846Ω·cm and a relatively high hole concentration of 5.100 × 10^17 cm^-3 at room temperature.     

金属有机物化学气相沉积法生长Ga2（1-x）In2xO3薄膜的结构及光电性能研究

采用金属有机物化学气相沉积（MOCVD）法在蓝宝石（0001）衬底上制备出了Ga_2（1-x）In_2xO₃（x=01—09）薄膜,研究了薄膜的结构、电学和光学特性以及退火处理对薄膜性质的影响.测量结果表明：当In组分x=02时,样品为单斜β-Ga₂O₃结构;x=05的样品,薄膜呈现非晶结构,退火处理后薄膜结构得到明显的改善 关键词： 金属有机物化学气相沉积 2（1-x）In_2xO₃薄膜')" href="#">Ga_2（1-x）In_2xO₃薄膜 蓝宝石衬底 退火