We deposited plasma-enhanced chemical vapor deposition silicon carbon nitride ͑SiC x N y ͒ antireflection coating and passivation layers using a silane-free process. We used a solid polymer source developed at SiXtron Advanced Materials to eliminate the storage and handling of dangerous pyrophoric silane gas. We used ammonia flow rate as a control for the chemical and optical properties in the silane-free process. As NH 3 flow rate increases, the carbon content, refractive index, extinction coefficient, and surface charge density of the film decrease. At an ammonia flow rate of 3000 sccm, which is similar to the conventional SiN x , the extinction coefficients for the two films were similar. This led to an emitter dark saturation current density ͑J oe ͒ of 404 fA/cm 2 for the two films on 45 ⍀/ᮀ emitters. However, a stack passivation of SiO 2 /SiC x N y on an 80 ⍀/ᮀ emitter resulted in an emitter dark saturation current density of 95 fA/cm 2 , which is enough to provide a good surface passivation for high efficiency solar cells. An energy conversion efficiency of 17.4% was obtained for a 149 cm 2 textured Czochralski screen-printed solar cell with this stack passivation. For a 156 cm 2 nontextured multicrystalline silicon, with only SiC x N y and a 45 ⍀/ᮀ emitter, we obtained 14.9% efficiency.

Phosphoric acid was used an n-type doping source to make an emitter for silicon solar cells. This paper reports on a cold spray method to coat phosphoric acid on the silicon wafer without any additional complicated and corrosive heating system. The key spray parameters such as belt speed, flow rate of the carrier gas, and concentration of phosphoric acid are optimized to get uniform and reproducible sheet resistance for the emitter. The diffusion process has been studied by firing silicon wafers that are spraycoated with phosphoric acid. screen printed solar cells have been fabricated using the emitter formed by the spray coating. The effects of the emitter on cell performance have been investigated and compared with those of the conventional POCl 3 -diffused emitter. screen printed/spray-diffused cells give impressive cell efficiencies of ϳ16.6% on 1 ⍀ cm float zone wafers, which is nearly equal to those of POCl 3 emitter cells ͑ϳ16.9%͒. Compared with the POCl 3 emitter cell, the spray-diffused cells show slightly lower quantum efficiency at the short-wavelength response and slightly higher emitter saturation current density ͑ϳ3.59 ϫ 10 −13 A/cm 2 compared with 2.73 ϫ 10 −13 A/cm 2 ͒. Further optimization can eliminate this small difference in efficiency.The emitter in a solar cell collects minority carriers generated in the substrate and requires low surface recombination velocity and uniform sheet resistance for high performance. Efforts have been made to develop a cost-effective phosphorus diffusion process because the emitter diffusion for solar cells can influence the throughput of the solar cell fabrication line, bulk lifetime of the processed wafer, and emitter quality of the solar cell. Batch-type diffusion processing using phosphorus oxychloride ͑POCl 3 ͒ in a tube furnace is frequently used for junction formation in photovoltaics ͑PV͒ industries because of low contamination and the availability of equipment from the semiconductor industry. However, the cost and throughput of a POCl 3 diffusion system are not satisfactory because of the prolonged heat-treatment and excessive wafer handling, including wafer insertion into the quartz boats. To meet the requirements of the PV industry, including low cost, high throughput, and high mechanical yield, a high-quality inline-type diffusion process and equipment need to be developed. Although various phosphorus diffusion techniques 1-5 have been reported for PV applications, no systematic study on the cold spray of phosphoric acid has been conducted. In this paper, the spray diffusion is carried out in an IR belt furnace after applying the phosphoric acid coating in a continuous cold spray system. The cold spray of phosphoric acid offers many advantages over conventional diffusion technology because of its simplicity, high throughput, and low cost. Furthermore, spray diffusion makes it possible to have versatile process sequence because the doping source is coated only on one side.To form phosphorus pentoxide ͑P 2 O 5 ͒ on the surface of a silicon wafer, phospho...

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