Influence of RF-power on the optical, structural, and morphological properties of ZnS:Cr thin films

ABSTRACT

In this work, the morphological, optical, and structural properties of ZnS:Cr films deposited by RF-sputtering are examined for different RF-powers. For this, thin films (ZnS) and (ZnS:Cr) were deposited on glass and Si substrates. The deposition time was set at 90 min, and the RF power varied in the range of 100–200 W. X-ray indicated that all the ZnS films were single-phase with apreferred growth orientation along the (111) plane of the (ZB) phase. The Cr-doped ZnS, and showed the (111) (2 20) and (311) peaks of the same phase. The ZnS films showed acrystallite size of 25.45 nm for RF power of 200 W. While in the case of ZnS:Cr, the crystallite size increased from 16.6 nm to 28.5 nm. The strain was shown to decrease from 2.2 × 10⁻³ to 1.45 × 10⁻³. SEM observations revealed smooth film surfaces. (EDS) revealed that the Cr rate is smaller than the Zn and Srates. UV- measurements revealed that the ZnS films exhibit an average transmittance on the order of 70% whilst that the ZnS:Cr was less than 60% in the visible wavelength region. Moreover, the optical bandgap of the ZnS films was found to be equal to 3.57 eV, and decreases for ZnS:Cr.

KEYWORDS:

• ZnS:Cr
• intermediate bandgap
• chromium-doped zinc sulphur
• thin films
• radio frequency sputtering

Disclosure statement

No potential conflict of interest was reported by the author(s).