Study of Nano-Scale Electrical Properties of Hydrogenated Microcrystalline Silicon Solar Cells by Conductive Atomic Force Microscope

Abstract

The nano-scale current–voltage (I–V) characteristics of hydrogenated microcrystalline silicon (µc-Si:H) solar cells were studied by conductive atomic force microscope (conductive AFM) for the first time. A large local reverse (leakage) current was observed at a grain boundary, which was measured during the detection of the surface topography of a µc-Si:H solar cell in the contact mode. The grain boundary of the µc-Si:H solar cell might behave similarly to a current leakage path. In conductive AFM measurement, we found that surface topography of the µc-Si:H solar cell is composed of large convex regions. Here, a large convex region is formed by the aggregation of small grains with a diameter of ∼20 nm, which is similar to that of a silicon nanocrystallite determined by X-ray diffraction (XRD) measurement. We successfully evaluated the relationship between the nano-scale electrical properties and characteristics of grain boundaries. The obtained result indicates that the nano-scale quality of the µc-Si:H solar cell can be characterized by conductive AFM with a high experimental resolution of ∼1 nm.