Department of Photonics and Institute of Electro-optical Engineering, National Chiao-Tung University, Hsinchu, 30010 Taiwan, Republic of China.
ACS Nano. 2013 Aug 27;7(8):7318-29. doi: 10.1021/nn402976b. Epub 2013 Aug 19.
We present systematic works in characterization of CIGS nanotip arrays (CIGS NTRs). CIGS NTRs are obtained by a one-step ion-milling process by a direct-sputtering process of CIGS thin films (CIGS TF) without a postselenization process. At the surface of CIGS NTRs, a region extending to 100 nm in depth with a lower copper concentration compared to that of CIGS TF has been discovered. After KCN washing, removal of secondary phases can be achieved and a layer with abundant copper vacancy (V(Cu)) was left. Such compositional changes can be a benefit for a CIGS solar cell by promoting formation of Cd-occupied Cu sites (Cd(Cu)) at the CdS/CIGS interface and creates a type-inversion layer to enhance interface passivation and carrier extraction. The raised V(Cu) concentration and enhanced Cd diffusion in CIGS NTRs have been verified by energy dispersive spectrometry. Strengthened adhesion of Al:ZnO (AZO) thin film on CIGS NTRs capped with CdS has also been observed in SEM images and can explain the suppressed series resistance of the device with CIGS NTRs. Those improvements in electrical characteristics are the main factors for efficiency enhancement rather than antireflection.
我们提出了 CIGS 纳米尖阵列（CIGS NTR）的系统工作。CIGS NTR 通过 CIGS 薄膜（CIGS TF）的直接溅射工艺一步离子铣削工艺获得，而无需后硒化工艺。在 CIGS NTR 的表面，发现了一个深度延伸至 100nm 的区域，与 CIGS TF 相比，铜浓度较低。在 KCN 洗涤后，可以去除二次相，并留下富含铜空位（V（Cu））的层。这种成分变化可以通过在 CdS/CIGS 界面处促进 Cd 占据的 Cu 位（Cd（Cu））的形成和创建一个类型反转层来增强界面钝化和载流子提取，从而有利于 CIGS 太阳能电池。能量色散光谱已验证了 CIGS NTR 中 V（Cu）浓度的升高和 Cd 扩散的增强。SEM 图像还观察到用 CdS 覆盖的 CIGS NTR 上的 Al:ZnO（AZO）薄膜的附着力增强，这可以解释具有 CIGS NTR 的器件的串联电阻降低。这些电特性的改善是效率提高的主要因素，而不是抗反射。
