Transparent and conducting p-type (CuS)x:(ZnS)1-x thin films produced by thermal evaporation: An efficient broadband Si heterojunction photodiode

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Kaplan H. K., Akay S. K.

APPLIED SURFACE SCIENCE, no.652, pp.1-13, 2024 (SCI-Expanded)

  • Publication Type: Article / Article
  • Publication Date: 2024
  • Doi Number: 10.1016/j.apsusc.2024.159330
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Page Numbers: pp.1-13
  • Bursa Uludag University Affiliated: Yes


This study demonstrates the viability of the thermal evaporation method to produce transparent and highly conductive p-type (CuS)x:(ZnS)1-x thin films by achieving the highest conductivity value (1.4 × 103 S/cm) reported in this field to date. This places it in direct comparison with n-type transparent conductors. Analysis through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) unveils nanocomposite structures comprising sphalerite ZnS, chalcocite Cu2S, and covellite CuS nanocrystals in the thin films. The study reveals that transmittance values at a wavelength of 550 nm vary from 84 % to 65 % based on the increasing CuS ratio, establishing thermal-evaporated (CuS)x:(ZnS)1-x thin films as promising candidates for p-type transparent electrodes.

Moreover, p+-(CuS)0.49:(ZnS)0.54/n-Si heterojunction photodiodes were also produced. The heterojunction diode exhibited excellent photo-response characteristics in a wide range of wavelengths between 325 and 1170 nm at zero-bias. The responsivity value of the photodiode was as high as 1.44 A/W at the peak wavelength of 912 nm (9.45 mW/cm2) with a high Ion/Ioff ratio of 1.45 × 104. Besides, it was shown to have excellent detectivity, response time, and external quantum efficiency (EQE) values corresponding to 2.62 × 1012 Jones, 8.45 µs, and 244 %, respectively. Most of these values are superior to those even in commercial-grade photodiodes.