电弧放电法制备SiC纳米丝的实验研究

电弧放电法实验制备了碳化硅纳米丝.在6 mm的石墨棒中心钻一个4 mm的孔,将50at.%C 50at.%SiO2的粉末充分混合,填入其中作电弧放电阳极,水冷铜靶作阴极,放电电流70 A,收集放电后产生的粉末,用XRD、激光拉曼光谱、SEM、TEM进行分析.SEM和TEM照片表明其中有大量的实心纳米丝,其直径30 nm～50 nm,长度5 μm以上,XRD分析表明其为β-SiC,拉曼光谱中在785 cm-1有一个尖锐峰.我们认为碳纳米管与气态的SiO2反应生成了SiC纳米丝.     

Modulation of luminescence emission spectra of N-doped ß-Ga2O3 nanowires by thermal evaporation

In this study, we have synthesized N-doped ß-Ga₂O₃ nanowires on a p-type Si (100) substrate at the temperature of 850 °C through evaporation to modulate the spectra of the luminescence emission. Both TEM and XRD analyses confirmed that N-doped ß-Ga₂O₃ is monoclinic with a uniform mean diameter of 30 nm and a length up to several tens of micrometers. As determined by selected area diffraction (SAD), the growth direction of N-doped ß-Ga₂O₃ nanowires is [002]. The optical properties of the N-doped ß-Ga₂O₃ nanowires were studied by cathodoluminescence (CL) at the 10 and 300 K, exhibiting a UV and red light emission as a function of the nitrogen dopant. The results serve to reinforce the potential of N-doped ß-Ga₂O₃ nanowires for optoelectronic device applications.     

Cover Picture: Direction‐Dependent Homoepitaxial Growth of GaN Nanowires (Adv. Mater. 2/2006)

GaN nanowires with vastly different morphologies depending upon their growth direction can be produced by direct nitridation and vapor transport of Ga in disassociated ammonia, report Sunkara and co‐workers on p. 216. Nanowires grown along the c‐direction develop hexagonal‐prism island morphologies, while wires grown along the a‐direction form uniform, belt‐shaped morphologies. A “ballistic” phenomenon involving the 1D transport of adatoms on the non‐polar surfaces of <0001> GaN nanowires is proposed to explain the prismatic island morphologies.