Transformation from β-Ga2O3 to GaN Nanowires via Nitridation

Element doping is an important way to modify the properties of semiconductor materials. In our previous work, it was found that nitrogen-doping in β-Ga2O3 nanowires can induce a novel luminescence emission （around 740 nm） caused by generation of acceptor levels at the middle of the band gap of the β-Ga2O3 nanowires. Here we report that further heavy doping of nitrogen can transform the β-Ga2O3 nanowires completely into wurtzite structured GaN nanowires. Transmission electron microscopy （TEM）, x-ray diffraction （XRD） and Raman spectrum are used to evaluate the transition process. Both XRD and Raman analysis reveal that the monoclinic β-Ga2O3 nanowires start phase transformation at a temperature around 850℃ towards wurtzite structured GaN. Our results will be very helpful to profound our understanding of the doping induced effects and phase transformation in semiconductor compounds.     

Room Temperature Ferromagnetism and Optical Tunability in Cu Doped GaN Nanowires

GaN nanowires doped with 2at.% and 6at.% Cu ions are synthesized by chemical vapour deposition method. Structural and compositional analyses demonstrate that the as-grown nanowires are of single crystal wurtzite GaN structure. Magnetic characterizations reveal that the doped GaN nanowires exhibit room temperature ferromagnetism. The measured saturation magnetic moments are 0.37ug and 0.47ug per Cu atom at 300 K for Cu 2 at. % and 6 at. %, respectively. The photoluminescence spectra show that Cu dopant can tune the band gap of the GaN, which leads to a red shift of band-edge emission with increasing dopant concentration.     

高分辨单颗粒分析在生物样品中的应用

冷冻电子显微学作为结构生物学主要工具之一,以解析承担生命活动中重要功能的各种蛋白质机器三维结构为手段,对其在生命活动中的功能机制进行研究。冷冻电子显微学的单颗粒分析法具有分辨率高、生物样品无需结晶、解析的结构接近生理状态等优点。近几年来,随着软、硬件的发展与革新,高分辨冷冻电镜单颗粒分析法在生物样品上的应用范围方面得到进一步扩展,囊括大至上百纳米的病毒颗粒,小至十纳米左右的蛋白质机器,同时单颗粒分析的分辨率也在稳步提高。目前,大量生物样品的结构解析能够常态地达到3~4 Å的准原子分辨率,足以阐明大部分生物问题。文章简要介绍了单颗粒分析的理论基础、发展过程、研究现状以及面临的更多挑战。     

ZnO纳米棒阵列的同步法制备及其PL性能研究

在较低温度下，采用化学法在Zn片和玻璃片上同步制备了ZnO纳米棒阵列。利用XRD、FESEM和HRTEM对样品进行了表征，并且通过光致发光谱研究了阵列的光致发光(PL)性能。结果表明，ZnO纳米棒阵列较为致密、取向性较好。纳米棒为六方纤锌矿相，沿c轴生长，平均直径约为60 nm。同步法制备的2种ZnO纳米棒阵列均具有较好的紫外和橙红色发光性能，但发光特性却存在一定差异，这可能主要是由于2种阵列中纳米棒的缺陷含量不同所致。