Three-Dimensional Emitter Based on Locally Enhanced Diffusion (TREBLE) Structure: Modeling and Formation

摘要

Here we present a new concept called TREBLE, ThRee-dimensional Emitter Based on Locally Enhanced diffusion, that can be applied to fine-grained polycrystalline silicon solar cells. The concept makes use of the columnar structure of polycrystalline layers and of preferential doping created by dopants diffusion along grain boundaries during formation of the emitter. We first experimental data on phosphorus diffusion in our polysilicon materials and on the carrier collection on such pc-Si based cells. The spectral responses indicates that collection is dominated by the emitter's three dimensional structure. Then, we present a two-dimensional device simulation of an ideal cell using a 2D simulator ISE-DESSIS with the junction depth along grain boundaries (X_(gb)) as the main parameter. The calculations show that cell efficiencies up to 10% for quite high X_(gb) values (> 4μm) are expected on such highly defective polysilicon material.