Electrical and optical properties of sub-10 nm nickel silicide films for silicon solar cells

• Published in: Journal of physics. D, Applied physics Applied physics, 2017-01, Vol.50 (3), p.35102
• Main Authors: Brahmi, Hatem, Ravipati, Srikanth, Yarali, Milad, Shervin, Shahab, Wang, Weijie, Ryou, Jae-Hyun, Mavrokefalos, Anastassios
• Format: Article
• Language: English
• Subjects: Drude-model; nickel silicide; p-type conductor; reflectance; refractive index; transparent conductor; ultra-thin film
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/1361-6463/50/3/035102

Highly conductive and transparent films of ultra-thin p-type nickel silicide films have been prepared by RF magnetron sputtering of nickel on silicon substrates followed by rapid thermal annealing in an inert environment in the temperature range 400-600 °C. The films are uniform throughout the wafer with thicknesses in the range of 3-6 nm. The electrical and optical properties are presented for nickel silicide films with varying thickness. The Drude-Lorentz model and Fresnel equations were used to calculate the dielectric properties, sheet resistance, absorption and transmission of the films. These ultrathin nickel silicide films have excellent optoelectronic properties for p-type contacts with optical transparencies up to 80% and sheet resistance as low as ~0.15 µ cm. Furthermore, it was shown that the use of a simple anti-reflection (AR) coating can recover most of the reflected light approaching the values of a standard Si solar cell with the same AR coating. Overall, the combination of ultra-low thickness, high transmittance, low sheet resistance and ability to recover the reflected light by utilizing standard AR coating makes them ideal for utilization in silicon based photovoltaic technologies as a p-type transparent conductor.