Çetinel Alper, Utlu Gokhan
Department of Physics, Ege University, Bornova, 35030 Izmir, Turkey.
ACS Omega. 2023 May 31;8(23):20801-20809. doi: 10.1021/acsomega.3c01438. eCollection 2023 Jun 13.
CuO/ZnO heterojunction was fabricated on porous silicon (PSi) by a two-step electrochemical deposition technique with changing current densities and deposition times, and then the PSi/CuO/ZnO nanostructure was systematically investigated. SEM investigation revealed that the morphologies of the ZnO nanostructures were significantly affected by the applied current density but not those of CuO nanostructures. It was observed that with the increase of current density from 0.1 to 0.9 mA/cm, ZnO nanoparticles showed more intense deposition on the surface. In addition, when the deposition time increased from 10 to 80 min, at a constant current density, an intense ZnO accumulation occured on CuO structures. XRD analysis showed that both the polycrystallinity and the preferential orientation of ZnO nanostructures change with the deposition time. XRD analysis also revealed that CuO nanostructures are mostly in the polycrystalline structure. Several strong CuO peaks were observed for less deposition times, but those peaks diminish with increasing deposition time due to ZnO contents. According to XPS analysis, extending the deposition time from 10 to 80 min, the intensity of the Zn peaks increases, whereas the intensity of the Cu peaks decreases, which is verified by the XRD and SEM investigations. It was found from the - analysis that the PSi/CuO/ZnO samples exhibited rectifying junction and acted as a characteristical p-n heterojunction. Among the chosen experimental parameters, PSi/CuO/ZnO samples obtained at 0.5 mA current density and 80 min deposition times have the best junction quality and defect density.
通过两步电化学沉积技术，在改变电流密度和沉积时间的条件下，在多孔硅（PSi）上制备了CuO/ZnO异质结，然后对PSi/CuO/ZnO纳米结构进行了系统研究。扫描电子显微镜（SEM）研究表明，ZnO纳米结构的形态受施加的电流密度影响显著，而CuO纳米结构的形态则不受影响。观察到，随着电流密度从0.1 mA/cm增加到0.9 mA/cm，ZnO纳米颗粒在表面的沉积更加密集。此外，当沉积时间从10分钟增加到80分钟时，在恒定电流密度下，CuO结构上出现了强烈的ZnO堆积。X射线衍射（XRD）分析表明，ZnO纳米结构的多晶性和择优取向都随沉积时间而变化。XRD分析还表明，CuO纳米结构大多为多晶结构。在沉积时间较短时观察到几个较强的CuO峰，但由于ZnO含量的增加，这些峰随着沉积时间的增加而减弱。根据X射线光电子能谱（XPS）分析，将沉积时间从10分钟延长到80分钟，Zn峰的强度增加，而Cu峰的强度降低，这一点通过XRD和SEM研究得到了验证。从分析中发现，PSi/CuO/ZnO样品表现出整流结，并且起到了典型的p-n异质结的作用。在所选的实验参数中，在0.5 mA电流密度和80分钟沉积时间下获得的PSi/CuO/ZnO样品具有最佳的结质量和缺陷密度。
