A novel approach toward the simultaneous diffusion of boron and phosphorus in silicon
- Georgia Inst. of Tech., Atlanta, GA (United States). Dept. of Electrical and Computer Engineering
A novel technique is described for simultaneously diffusion boron and phosphorus on opposite sides of a silicon wafer for the fabrication of simple, high-efficiency solar cells. The solid doping sources used in this approach are fabricated using standard POCl{sub 3} and BBr{sub 3} liquid sources and can be tailored to produce a wide range of boron and phosphorus diffusion profiles for a fixed thermal diffusion cycle. Uniformity of sheet resistance across a 49 cm{sup 2} area is greater than 95% in many cases. Unique to this approach is that the resulting diffusion glass is extremely thin, which allows for the in situ growth of a thin thermal oxide for surface passivation, without appreciably increasing the reflectance of the solar cell after applying the antireflection coating. Measurements of the saturation current density (J{sub o}) by the photoconductance decay technique gave a low J{sub o} of 33.3 fA/cm{sup 2} for a phosphorus-diffused sample with in situ oxide surface passivation, and a J{sub o} of 292 fA/cm{sup 2} for a boron-diffused sample. Initial solar cell fabrication experiments with simple, untextured n{sup +}pp{sup +} structures have produced efficiencies as high as 17%, displaying fill factors of 0.79 and shunt resistances greater than 65,000 {Omega}-cm{sup 2}, demonstrating that no detectable cross-doping takes place during this new simultaneous boron and phosphorus diffusion technique.
- OSTI ID:
- 452234
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 1; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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