Promising Shadow MaskingTechnique for the Deposition ofHigh-Efficiency Amorphous SiliconSolar Cells Using Plasma-EnhancedChemical Vapor DepositionK

摘要

In this work, a detailed description of the various steps involved in the fabrication of highefficiency hydrogenated amorphous-silicon cells using plasma-enhanced chemical vapordeposition, and a novel shadow masking technique is presented. The influence of thedifferent masking methods on the cell parameters was experimentally investigated.Particularly, the short-circuit current density (Jsc), the fill factor, the open circuit voltage(Voc), and the resistive losses indicated by the shunt (Rsh) and series (Rs) resistances weremeasured in order to assess the performance of the cells as a function of the masks usedduring the cell fabrication process. The results indicate that the use of a masking techniquewhere the p-i-n structure was first deposited over the whole surface of a 20 cm2 × 20 cm2substrate, followed by the deposition, deposits the back contact through a metal mask,and by the ultrasonic soldering of indium to access the front contact is a good alternative tolaser scribing in the laboratory scale. Indeed, a record efficiency of 8.8%, with a shortcircuit current density (Jsc) of 15.6 mA/cm2, an open-circuit voltage (Voc) of 0.8 V, and a fillfactor of 66.07% and low resistive losses were obtained by this technique. Furthermore, aspectroscopic ellipsometry investigation of the uniformity of the film properties (thickness,band gap, and refractive index) on large-area substrates, which is crucial to mini-modulefabrication on a single substrate and for heterojunction development, was performed usingthe optimal cell deposition recipes. It was found that the relative variations of the band gap,thickness, and refractive index n are less than 1% suggesting that the samples are uniformover the 20 cm2 × 20 cm2 substrate area used in this work.