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

Abstract

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.

High Passivation Performance of Cat-CVD i-a-Si:H Derived from Bayesian Optimization with Practical Constraints

“…The BO in this study optimized the passivation quality under the i-a-Si:H deposition conditions. We have previously reported that τ eff increases with increasing i-a-Si:H thickness . Thus, we modeled τ eff as a function of the thickness in addition to the deposition condition in model 1.…”

“…We have previously reported that τ eff increases with increasing i-a-Si:H thickness. 22 Thus, we modeled τ eff as a function of the thickness in addition to the deposition condition in model 1. A BO with no constraints may converge to the conditions under which thick i-a-Si:H is deposited.…”

Improvement in passivation quality and open-circuit voltage in silicon heterojunction solar cells by the catalytic doping of phosphorus atoms

“…[17][18][19][20][21][22][23] This novel doping technique, referred to as "Cat-doping", can be performed at significantly low substrate temperatures of less than 200°C, and is thus applicable to the fabrication of a-Si= c-Si heterojunction solar cells. We have already confirmed the effectiveness of P Cat-doping in reducing the SRV of minority carriers on n-type c-Si wafers.…”

“…We have already confirmed the effectiveness of P Cat-doping in reducing the SRV of minority carriers on n-type c-Si wafers. 17,18,[21][22][23] In this study, we attempt to apply P Cat-doping to actual a-Si=c-Si heterojunction solar cells. A solar cell prepared with P Catdoping shows better V oc than a cell without P Cat-doping, indicating the applicability of Cat-doping to actual solar cell devices.…”

Realization of radial p-n junction silicon nanowire solar cell based on low-temperature and shallow phosphorus doping

“…It was demonstrated that HWCVD has the advantages of conformal film deposition on small objects with high-aspect ratio structure [24,25] and no ion bombardment, which make it suitable for fabrication of devices with SiNW structure. Moreover, HWCVD technique can be used to form shallow doping layer (less than 10 nm in depth) on single-crystal silicon surface at temperatures less than 350°C by catalytically generated phosphorous radicals from hot filaments [26-29]. …”