Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiNx films by introducing phosphorous catalytic-doped layer

Abstract

We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiNx) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH3 molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiNx/P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiNx passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiNx films. The outstanding results obtained imply that SiNx/P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.

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

“…1 is that P Cat-doping is effective in improving τ eff and implied V oc , as has been reported previously. 17,18,[21][22][23] When focusing on the T cat dependence of τ eff and implied V oc , τ eff and implied V oc show maximum values at T cat of around 900 °C.…”

“…[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.…”

“…We have recently demonstrated that an ultrathin (<5 nm) phosphorus-(P-) doped layer can be formed on a c-Si surface by exposing c-Si to P-related radicals generated by decomposing PH 3 molecules on a heated catalyzing wire. [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.…”

Passivation effect of ultra-thin SiN x films formed by catalytic chemical vapor deposition for crystalline silicon surface

“…16,17) Cat-CVD can realize low-damage deposition of passivation films due to its plasma-damage-less nature, and we have thus far demonstrated high-quality passivation films formed by Cat-CVD. [18][19][20][21][22][23][24] In this study, we attempt to form ultra-thin SiN x films aiming at the utilization of the SiN x as the substitute of tunneling SiO 2 in the TOPCon structure.…”