Electronic and optical properties of CdS films deposited by evaporation

• CdS films are grown by the ultra-high vacuum evaporation.
• CdS film here with the high carrier density reaches to 1018 cm−3 is obtained.
• The film has low resistivity, which is as low as 2 Ω∙ cm.
• The optical band gap become wider from 2.42 eV to 2.54 eV.

CdS films grown by thermal evaporation on glass substrate under ultra-high vacuum are prepared with varying the growth temperature and atmosphere environment. The minimum resistivity of the films is as low as 2.0 Ω·cm, and the carrier density even reaches 1.6 × 1018 cm−3, which is much less than that prepared by the chemical bath deposition (CBD) method. The transmittance and band gap increase with the set the argon atmosphere and the growth temperature in the optimum value. Our results indicate the CdS films grown by evaporation at high vacuum may be more suitable for the application in optoelectronic devices, such as the solar cell materials.

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