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Investigation on copper doped CdTe thick films for optoelectronic applications: structural, optical and electrical characteristics |
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PP: 235-247 |
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doi:10.18576/ijtfst/130308
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Author(s) |
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Khairiah Alshehri,
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Abstract |
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| This study focuses on the effects of replacement Cd with Cu on the structural, optical, and electrical properties of CdTe one micron thin film. In this regard, CdTe ingots with Cu concentrations from 0 to 10 at.% were produced via mechanical ball milling at 200 rpm for 6 hours, then shaped into disks for thin film deposition. Films with a 1000 nm thickness were deposited onto glass substrates by electron beam at room temperature, after cleaning and evacuating the chamber to 510−6 Pa. XRD and EDXS analyses confirmed Cu incorporation and retention of the cubic structure. In terms of spectral ellipsomeric, three optical layer models (adhesive layer of the substrate/B-spline layer of CdTe:Cu film/surface roughness layer) are used to determine the thickness of the film with high accuracy. Optical measurements showed that increasing Cu content led to larger crystallite sizes, reduced micro-strain, and a blue shift in the absorption edge, indicating a wider band gap. Refractive index and extinction coefficient calculations revealed a decrease in refractive index with higher Cu doping, suggesting improved transparency and favorable band gap characteristics for photovoltaic applications. Electrical measurements using the four-point probe method showed that increasing Cu content from 0 to 10 at.% decreased sheet resistance from 49.9 Ω to 1.65 Ω and increased conductivity from 200 (Ω.cm)−1 to 6000 (Ω.cm)−1. Carrier concentration and Hall mobility were also improved, suggesting that CdTe films with 10 at.% Cu are optimal for high-efficiency CdTe solar cells.
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