Annealing effects on physical properties of doped CdTe thin films for photovoltaic applications
- Resource Type
- Authors
- Muhammad Anis-ur-Rehman; G.H. Tariq
- Source
- Materials Science in Semiconductor Processing. 30:665-671
- Subject
- Materials science
Dopant
Band gap
Annealing (metallurgy)
Mechanical Engineering
Photoconductivity
Doping
Analytical chemistry
Condensed Matter Physics
Cadmium telluride photovoltaics
Condensed Matter::Materials Science
symbols.namesake
Mechanics of Materials
Condensed Matter::Superconductivity
symbols
General Materials Science
Thin film
Raman spectroscopy
- Language
- ISSN
- 1369-8001
Polycrystalline Cadmium Telluride (CdTe) thin films were prepared on glass substrates by thermal evaporation at the chamber ambient temperature and then annealed for an hour in vacuum ~1×10−5 mbar at 400 °C. These annealed thin films were doped with copper (Cu) via ion exchange by immersing these films in Cu (NO3)2 solution (1 g/1000 ml) for 20 min. Further these films were again annealed at different temperatures for better diffusion of dopant species. The physical properties of an as doped sample and samples annealed at different temperatures after doping were determined by using energy dispersive x-ray analysis (EDX), x-ray diffraction (XRD), Raman spectroscopy, transmission spectra analysis, photoconductivity response and hot probe for conductivity type. The optical band gap of these thermally evaporated Cu doped CdTe thin films was determined from the transmission spectra and was found to be in the range 1.42–1.75 eV. The direct energy band gap was found annealing temperatures dependent. The absorption coefficient was >104 cm−1 for incident photons having energy greater than the band gap energy. Optical density was observed also dependent on postdoping annealing temperature. All samples were found having p-type conductivity. These films are strong potential candidates for photovoltaic applications like solar cells.