Hydrogen passivation of poly-Si/SiOx contacts for Si solar cells using Al2O3 studied with deuterium

Abstract

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Implantation‐based passivating contacts for crystalline silicon front/rear contacted solar cells

“…In particular, we measured τ eff = 4.6 ms, J 0 = 14.5 fA/cm 2 , and iV OC > 700 mV. Sample n3 benefits from the FGA treatment owing to the diffusion of H + atoms into the stack, enhancing chemical passivation at the c‐Si/SiO 2 interface . Similar results about FGA have been reported in Peibst et al, although in our case, the implantation dose is higher than typical literature values with similar annealing conditions.…”

“…Sample n3 benefits from the FGA treatment owing to the diffusion of H + atoms into the stack, enhancing chemical passivation at the c-Si/SiO 2 interface. 42,56 Similar results about FGA have been reported in Peibst et al, 57 although in our case, the implantation dose is higher than typical literature values 58,59 with similar annealing conditions. Next, we investigate the effect of poly-Si layer thickness on passivation.…”

“…Annealing temperature for samples in Figure A,B is either 950°C or 850°C, and annealing time is variable between 5 and 90 minutes, depending on the thickness of the poly‐Si layer. Eventually, a forming gas annealing (FGA) at 400°C for 2 hours (10% H 2 in N 2 ) is performed to enhance chemical passivation at c‐Si/SiO 2 interface . Quasi‐steady‐state photoconductance lifetime measurements (QSSPC) are performed using a Sinton Instruments WCT‐120 on the symmetric samples in Figure A,B to assess the surface passivation quality of the fabricated structures.…”

“…Eventually, a forming gas annealing (FGA) at 400 C for 2 hours (10% H 2 in N 2 ) is performed to enhance chemical passivation at c-Si/SiO 2 interface. 42 Quasi-steady-state photoconductance lifetime measurements (QSSPC) 43 are performed using a Sinton Instruments WCT-120 on the symmetric samples in Figure 1A Solar cells are fabricated by combining the layer stacks optimized in a poly-poly configuration (see Figure 1C). The process is shown in Figure 2A), by covering the other side with 100-nm-thick SiN x protective layer.…”

Hydrogenation Mechanisms of Poly‐Si/SiOx Passivating Contacts by Different Capping Layers

“…Hydrogenation treatments in c‐Si solar cell technology are often performed via forming gas annealing (FGA) of samples in a mixture of H 2 and inert gas, by annealing the samples without any capping layers in a mixture of water vapor and N 2 , or by depositing hydrogen‐rich capping layers such as AlO x :H or SiN x :H and annealing them in N 2 or FGA. Previously, we have noticed that in the case of low‐resistivity substrates (1 Ω cm), FGA of poly‐Si/SiO x passivating contacts resulted in little performance improvement, whereas others have reported a noticeable improvement . However, when capping layers and postdeposition annealing treatments are used, the passivating‐contact performance improves significantly, as reported by many groups .…”