Effect of Radical-Doped n+ Back Surface Field Layers on the Effective Minority Carrier Lifetimes of Crystalline Silicon with Amorphous Silicon Passivation Layers Deposited by Catalytic Chemical Vapor Deposition

概要

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To reduce surface recombination at an amorphous silicon (a-Si)/crystalline silicon (c-Si) interface in heterojunction solar cells, a thin phosphorus-doped back surface field (BSF) layer is applied to c-Si. Thin BSF layers are doped at temperatures lower than 350 °C by radical doping. The reduction in the surface recombination velocity of n-type c-Si is investigated by comparing the effective minority carrier lifetimes of c-Si samples with and without doping. Using radical-doped BSF layers, the effective minority carrier lifetimes of the samples with the thin intrinsic a-Si passivation layers increase significantly. The change in effective minority carrier lifetime under the BSF layer doping condition is also investigated. An effective minority carrier lifetime of 1.6 ms is observed in the radical-doped sample with the 6-nm-thick intrinsic a-Si passivation layer. The high carrier concentration of the radical-doped BSF layers can also decrease the contact resistivity to a metal electrode. Therefore, the radical-doped BSF layers can be utilized for passivation and ohmic contact formation on the back surface of the heterojunction solar cells.
2012-10-25