Stephenson Institute for Renewable Energy, Liverpool University, Liverpool, L69 7ZF, UK.
Nanotechnology. 2013 Apr 5;24(13):135703. doi: 10.1088/0957-4484/24/13/135703. Epub 2013 Mar 12.
Defects in Au-catalysed CdTe nanowires vapour-liquid-solid-grown on polycrystalline underlayers have been critically evaluated. Their low-temperature photoluminescence spectra were dominated by excitonic emission with rarely observed above-gap emission also being recorded. While acceptor bound exciton lines due to monovalent metallic impurities (Ag, Cu or Na) were seen, only deeper, donor-acceptor-pair emission could be attributed to the Au contamination that is expected from the catalyst. Annealing under nitrogen acted to enhance the single crystal-like PL emission, whilst oxidizing and reducing anneals of the type that is used in solar cell device processing caused it to degrade. The incidence of stacking faults, polytypes and twins was related only to the growth axes of the wires (<111> 50%, <112> 30% and <110> 20%), and was not influenced by annealing. The potential electrical activity of the point and extended defects, and the suitability of these nanowire materials (including processing steps) for solar cell applications, is discussed. Overall they have a quality that is superior to that of thin polycrystalline films, although questions remain about recombination due to Au.
在多晶衬底上通过汽液固生长法生长的 Au 催化 CdTe 纳米线中存在的缺陷已得到了深入评估。它们的低温光致发光光谱主要由激子发射主导，很少观察到带隙以上的发射。虽然观察到了由于单价金属杂质（Ag、Cu 或 Na）引起的受主束缚激子线，但只能归因于 Au 污染的施主-受主-对发射，这是催化剂所预期的。在氮气中退火会增强单晶状 PL 发射，而在用于太阳能电池器件处理的氧化和还原退火会导致其退化。位错、多型体和孪晶的发生率仅与纳米线的生长轴（<111>50%、<112>30%和<110>20%）有关，而不受退火的影响。点缺陷和扩展缺陷的潜在电活性，以及这些纳米线材料（包括处理步骤）在太阳能电池应用中的适用性，都进行了讨论。总的来说，它们的质量优于多晶薄膜，尽管由于 Au 引起的复合问题仍有待解决。
