通信工程文献翻译——摘要：在无光照和有光照条件下，利用导电原子力显微镜（conductive - AFM）研究了氢化非晶硅（a-Si：H）太阳能电池的电流电压（I/V）特性。为了获得正确的I/V特性，通过直流溅射技术沉积20 nm厚的ZnO薄膜对导电AFM电极尖端进行修饰后，与非晶硅太阳电池的N层构成电连接。使其I/V特性从肖特基接触转换为欧姆接触。在N层和悬臂尖端之间的表面缺陷和氧化锌薄膜晶界处可能形成一个欧姆类电流路径。我们使用纳米尺度标准测量偏置电压为-2 V时的光电流图。在太阳能电池的纳米硅薄膜处出现了高光电流路径，与此同时在大小结晶粒子的边界处可以观察到小电流区域。这表明，边界氢钝化后具有高阻抗或可作为光电流重组中的漏电流路径。这些结果意味着，我们所提出的使用导电原子力显微镜与悬臂处覆盖氧化锌薄膜相结合的测量技术是一种对光电流短路路径检测的有效工具。此外，这些技术有助于提高薄膜太阳能电池的转换效率                                  

1 引言

近年，再生资源发电被看作是一种环境友好的发电技术，它已成为全球环境和能量需求之间的桥梁。作为候选之一，太阳能电池有很大的潜力，因为他们能直接将太阳能转换成电能。基于非晶（a-），纳米晶硅（nc-）和CIS(铜,铟,硒)的薄膜太阳能电池，与单晶硅太阳能电池在大批量、低成本生产的角度上相比，仍是很有前景的。然而，加速他们的使用和进一步改善这些薄膜太阳能电池的转换效率都是必要的。在纳米晶硅太阳能电池中，众所周知，纳米结构，如纳米晶粒，晶界和在薄膜中非晶结构都严重影响到了他们的电气特性。此外，在 (i-, n-, p-)层和硅太阳能电池(p/i, i/n)结点处有能降低太阳能转换效率的缺陷区域。此外，在太阳能电池的结晶粒子边界处应避免光电流载流子复合。虽然要求在纳米结构条件下观测，但由于纳米尺度测量的困难，他们并没有得到足够的研究。从这个意义上讲，期望能在纳米领域中开发出光伏特性表征方法。Fajfar等人利用导电原子力显微镜[2,3]，使纳米硅薄膜的研究已广泛进行。最近，我们已提出了用使用导电原子力显微镜和近场光学显微镜（SNOM）[4-7] 扫描纳米晶硅太阳电池的暗电流电压特性表征方法的一份报告。在此提出了与导电原子力显微镜有关的一种新的光照射系统和已被证实首次展示纳米分辨率敏感区的光伏特性的表征方法。

2 实验细节

2.1 导电原子力显微镜测量系统

图2-1导电原子力显微镜原理图与设计执行与纳I/V性能测试的样品：氢钝化非晶硅太阳能电池

图2-1显示了导电原子力显微镜（日本精工电子纳米，探测站技术： SPI3800N，单位：SPA-400）与新设计的用光照射来测量薄膜太阳能电池的I – V特性的样品架附件。卤素灯（白光）和LED（波长：625 nm）被用作为光源，用来促使太阳能电池光电流。为了使LED光照射到太阳能电池上，在导电原子力显微镜（AFM）上安装一个如图1所示的光纤夹具。并且LED贴于光纤尖端。光通过光纤传导，并在太阳能电池底部的前端旋转90度。太阳能电池表面的光斑直径约为2毫米。扫描悬臂......

abstract

Nano-scale current voltage (I–V) characteristics of hydrogenated amorphous silicon (a-Si:H) solar cells

were studied with and without light irradiations by using conductive Atomic Force Microscope (conductive-AFM). To obtain proper I–V characteristics, electrical contacts between the n-layer of the a-Si solar

cells and the cantilever of the AFM were modified by depositing ZnO films with the thickness of 20 nm on the tip using DC sputterer. The I–V characteristics were changed from Schottky like to ohmic like. Surface defects and grain boundaries of the ZnO thin film possibly formed an ohmic-like current path between n-layer and the tip of the cantilever. We measured photo-current map at the bias of 2 V with a resolution of nano-meter scales. High photo-current paths appeared at nano-crystallites formed in the nc-Si:H film of the solar cell while small current area was observed at the boundaries of the small and large grains. This suggests that the boundaries have high impedance created by hydrogen passivation or act as a leakage current path for the photo-current ecombination. These results imply that our proposed measurement technique using conductive-AFM combined with covering of ZnO film on the cantilever is a useful tool for the evaluation of the short path of the photo-current. In addition, these techniques contribute to increase the conversion efficiency of thin film solar cells.

1. Introduction

In recent years, electricity generations from renewable resources have been counted as a technique which is friendly with the environment and bridges the gaps between global demands and supplies of energies. As one of the candidates, solar cells have a good potential because of their direct-conversion technologies of solar energy into electricity. Thin film solar cells based on amor phous (a-), nano-crystalline (nc-) Si and CIS are promising devices in view points of large area and low cost productivities compared to the c-Si/poly c-Si solar cells [1]. However, further improvements

in the conversion efficiency of these thin film solar cells are necessary to accelerate their use. In the nc-Si solar cells, it is well known that nano-structures such as nano-crystallites, the grain boundaries and amorphous structure existing in the films affect severely to their electrical characteristics. In addition, there are defective areas in all (i-, n-, p-) layers and junctions (p/i, i/n) of the a-Si/nc-Si solar cells which reduce the conversion efficiencies. Further more, recombination of photo-generated carriers in grain boundaries should be avoided in the solar cells. Although the demands......