Experimental determination of base resistance contribution for point-like contacted c-Si solar cells using impedance spectroscopy analysis

Abstract

Abstract:One of the most common strategies in high-efficiency crystalline silicon (c-Si) solar cells for the rear surface is the combination of a dielectric passivation with a point-like contact to the base. In such devices, the trade-off between surface passivation and ohmic losses determines the optimum distance between contacts or pitch. Given a certain pitch, the series resistance related to majority carrier flow through the base and the rear point-like contact (R base ) is commonly calculated a-priori and not crosschecked in finished devices, since typical techniques to measure series resistance lead to an unique value that includes all ohmic losses. In this work, we present a novel method to measure R base using impedance spectroscopy (IS) analysis. The IS data at high frequencies allow to determine R base due to the presence of the capacitor formed by the metal/dielectric/semiconductor structure that covers most of the rear surface. The method is validated by device simulations where the dependence of R base on carrier injection, base resistivity and pitch are reproduced. Finally, R base is measured on finished devices. As a result, a more accurate value of the contacted area is deduced which is a valuable information for further device optimization.

Characterization of a Heterojunction Silicon Solar Cell by Means of Impedance Spectroscopy

“…According to the authors' conclusion, the solar cell responds to light impedance very sensitively, indicating that it would be a good fit for photosensor devices. In the paper by Orpella et al [22], the authors described a novel application of IS to measure the rear point contact (R base ) of a p-type silicon solar cell. These measurements at high frequencies enable the study of R base because they contain a capacitor consisting of a semiconductor, a dielectric and a metallic structure.…”

Thermal Conductivity Analysis of Amorphous Silicon Formed by Natural Cooling: A Molecular-dynamics Study

“…olycrystalline silicon (poly-Si) has been an attractive material for thin film transistors (TFTs) in active matrix liquid crystal displays 1) as well as thin film solar cells. 2) Due to the technological significance of large-grained poly-Si thin films, a lot of research has been devoted to studying the kinetics and the transformation mechanisms of the excimer-laser annealing (ELA) process. For applications of TFTs and solar cells, because residual grain boundaries in recrystallized Si degrade the electronic characteristics, especially the carrier mobility of TFTs, largegrained poly-Si is desired to realize high performance of devices.…”