Chang Feng-Ming, Brahma Sanjaya, Huang Jing-Heng, Wu Zong-Zhe, Lo Kuang-Yao
Department of Physics, National Cheng Kung University, Tainan, 701, Taiwan.
Sci Rep. 2019 Jan 29;9(1):905. doi: 10.1038/s41598-018-37601-8.
Although, post annealing is an efficient way to annihilate/restructure deficiencies in self-assembly (SA) ZnO nanorods (ZNRs), the detailed investigation about the surface properties of annealed SA-ZNRs is a long standing issue and the major discrepancy is mainly due to single step annealing. We demonstrate the strategic two step annealing process to create reliable structural configuration in SA-ZNRs during the first round of annealing at 800 °C in vacuum (VA process), and create intrinsic defects in the second step of annealing in oxygen rich atmosphere (OA process) to correlate the formation of the defects related to green/orange-red emission. SA-ZNRs annealed in VA-OA processes reveal positive correlations between the oxygen flow rate and formation of oxygen interstitials (O) and zinc vacancies (V). The OA-VA processes exhibit the relation of residual O and additional V. According to VA-OA and OA-VA processes, we propose that the green emission in ZnO annealed in oxygen poor/rich condition is mainly due to the formation of V/V and annealing at oxygen rich condition creates O that lead to strong orange-red emission. Rather than O1s, we propose a reliable method by considering the peak shift of Zn2p in XPS to inspect the ZnO matrix, which has good interdependence with the characteristics of PL.
尽管退火后处理是消除/重构自组装（SA）氧化锌纳米棒（ZNRs）缺陷的有效方法，但对退火后的SA-ZNRs表面性质的详细研究一直是个长期存在的问题，主要差异主要源于单步退火。我们展示了一种策略性的两步退火工艺，即在真空中于800°C进行第一轮退火（VA工艺）期间在SA-ZNRs中创建可靠的结构构型，并在富氧气氛中进行第二步退火（OA工艺）时产生本征缺陷，以关联与绿色/橙红色发射相关的缺陷形成。在VA-OA工艺中退火的SA-ZNRs显示出氧流量与氧间隙（O）和锌空位（V）形成之间的正相关。OA-VA工艺表现出残余O与额外V的关系。根据VA-OA和OA-VA工艺，我们提出在贫氧/富氧条件下退火的ZnO中的绿色发射主要归因于V/V的形成，而在富氧条件下退火会产生O，从而导致强烈的橙红色发射。我们提出一种可靠的方法，通过考虑XPS中Zn2p的峰移来检查ZnO基体，而不是O1s，它与PL的特性具有良好的相互依赖性。
