Phosphorus diffused LPCVD polysilicon passivated contacts with in-situ low pressure oxidation

Kinetics of Bulk Lifetime Degradation in Float‐Zone Silicon: Fast Activation and Annihilation of Grown‐In Defects and the Role of Hydrogen versus Light

“…Furthermore, it will be shown that the bulk lifetime can be stabilized against subsequent thermal processing at significantly lower temperatures (900 °C) than the conventionally used 30–60 min annealing at around 1050 °C. [ 12–16 ] The defect annihilation is also found to be fast (sub‐second timescale), although a fraction of the defects reappears during a subsequent degradation annealing. Together with N‐quantification measurements by secondary ion mass spectrometry (SIMS), it is concluded that at high temperatures the V x N y ‐centers dissociate, accompanied by an out‐diffusion of nitrogen from the Si‐wafer.…”

Improvement of Surface Passivation of Tunnel Oxide Passivated Contact Structure by Thermal Annealing in Mixture of Water Vapor and Nitrogen Environment

“…Tunnel oxide passivated contact (TOPCon) structures have shown excellent surface passivation with the outstanding implied open‐circuit voltage ( iV oc ) of higher than 740 mV and the single‐side surface saturated recombination current density ( J 0 ) of lower than 5 fA cm −2 . The excellent surface passivation is generally attributed to the chemical passivation of the interfacial oxide and the field‐effect passivation of the heavily doped polysilicon (poly‐Si) contact layer with a dopant diffusion tail into the crystalline silicon (c‐Si) wafer.…”

“…Generally, the fabrication of TOPCon structures on c‐Si wafers includes four major processes: 1) the fabrication of an ultrathin (≈1.5 nm) silicon oxide (SiO x ), 2) the deposition of highly doped amorphous silicon (a‐Si) or hydrogenated amorphous silicon (a‐Si:H), 3) the high‐temperature annealing for crystallization of the a‐Si:H layer and dopant activation, and 4) the hydrogenation for defect passivation. The SiO x can be made by various methods, such as acidic oxidation, thermal oxidation, mixed acid oxidation, ozone oxidation, and plasma‐assisted oxidation . All of these methods can produce good‐quality SiO x layers for effective surface passivation.…”

“…All of these methods can produce good‐quality SiO x layers for effective surface passivation. The doped a‐Si and a‐Si:H layers can be deposited by low‐pressure chemical vapor deposition (LPCVD) and by plasma‐enhanced chemical vapor deposition (PECVD) with either ex‐situ doping by ion implantation or diffusion or in‐situ doping by adding doping gases such as PH 3 for n‐poly‐Si and B 2 H 6 or B(CH) 3 for p‐poly‐Si . The crystallization and dopant activation can be done by thermal annealing at temperatures higher than 800 °C.…”

“…The crystallization and dopant activation can be done by thermal annealing at temperatures higher than 800 °C. The hydrogenation is normally carried out by the remote hydrogen plasma treatment, the annealing at moderate temperature (≈450 °C) in a so‐called forming gas, a hydrogen and nitrogen mixture environment, and the hydrogen‐containing thin‐film coatings following a moderate‐temperature annealing at around 450 °C . The hydrogen‐containing coatings such as SiN x :H and Al 2 O 3 could be deposited at relatively low temperature such as 200–400 °C and the hydrogen could be driven into the poly‐Si and poly/SiO x /c‐Si interface region during the firing process, which could be incorporated into the solar‐cell fabrication process.…”