四元AlInGaN的生长研究及降低内建电场的InGaN/AlInGaN多量子阱的实现

We have demonstrated the growth of quaternary AIlnGaN compounds at different growth temperatures and pressures with metalorganic chemical vapor deposition （MOCVD）. The optical properties of the samples have been investigated by photoluminescence （PL） at different temperatures. The results show that the sample grown at higher temperature （850℃） exhibits the best optical quality for its sharp band edge luminescence and weak yellow luminescence. The AIlnGaN exhibited three-dimensional （3D） growth mode at higher pressure. The band edge emission almost disappeared. With the optimization of AIInGaN growth parameters, we replaced the traditional barrier in InGaN/GaN multiple quantum wells （MQWs） with AllnGaN barriers. The peak wavelength for the InGaN/AIInGaN-MQW based light emitting diodes （LEDs） was very stable at various injection current levels because of the polarization-matched InGaN/AIInGaN MQWs.     

应用于铯原子喷泉钟的二维磁光阱研制

理论模拟研究了二维磁光阱原子束流量与饱和蒸汽压、冷却光强、激光失谐量的关系, 构建了二维磁光阱(2D-MOT)装置, 实验上实现了大流量的慢速原子束, 其测量值为2.1× 10⁹/s.利用荧光法测量了各实验参数与流量的关系, 测量结果与数值模拟结果符合较好. 关键词： 2D-MOT 流量 慢速原子束 铯原子喷泉钟     

Indium-Induced Effect on Polarized Electroluminescence from InGaN/GaN MQWs Light Emitting Diodes

Polarization-resolved edge-emitting electroluminescence （EL） studies of In GaN/GaN MQWs of wavelengths from near-UV （390nm） to blue （468nm） light-emitting diodes （LEDs） are performed. Although the TE mode is dominant in all the samples of InGaN/GaN MQW LEDs, an obvious difference of light polarization properties is found in the InGaN/GaN MQW LEDs with different wavelengths. The polarization degree decreases from 52.4% to 26.9% when light wavelength increases. Analyses of band structures of InGaN/GaN quantum wells and luminescence properties of quantum dots imply that quantum-dot-like behavior is the dominant reason for the low luminescence polarization degree of blue LEDs, and the high luminescence polarization degree of UV LEDs mainly comes from QW confinement and the strain effect. Therefore, indium induced carrier confinement （quantum-dot-like behavior） might play a major role in the polarization degree change of InGaN/GaN MQW LEDs from near violet to blue.     

基于CUDA的DCT快速变换实现方法

为了加快DCT快速变换的处理速度,提出了一种基于CUDA在图形处理器(GPU)上实现DCT快速变换的方法,其中主要利用DCT变换中各分块之间的独立性适合GPU并行处理架构的特点,把传统串行DCT快速变换算法映射到CUDA并行编程模型,并从线程分配,内存使用,硬件资源划分等方面进行优化,来充分利用GPU的巨大运算能力,实验表明,该方法能有效地提高D阻快速变换的速度.     

基于Zigbee的无线体感系统的设计与实现

介绍了一套基于Zigbee通信技术实现的无线体感系统。设计方案由前端传感器单元组建传感网络,采用ADXL345传感单元完成肢体运动信息的采集,采用PVDF压电薄膜脉搏传感器完成脉搏信息的采集;然后利用Zig-bee通信技术搭建无线通信网络,采用CC2430通信模块完成传感器数据至ARM处理器的传送;利用嵌入式ARM Cortex A8平台对来自不同传感器的不同信息进行处理,并将信息还原在Linux的图形界面下。     

蒙特卡罗方法研究光动力疗法选择性光损伤

为了研究光动力疗法选择性光损伤,采用蒙特卡罗方法,建立了组织中光动力剂量数学模型。得到光动力剂量随组织厚度增加呈指数衰减的结果。光动力损伤是阈值过程,对肿瘤组织造成深层光动力损伤时,更多正常组织受到损伤。光斑半径对对肿瘤组织损伤深度有明显影响。结果表明,适量光敏剂能引起浅薄全面的肿瘤组织光动力损伤,深层光动力损伤伴随正常组织损伤。