Quantum size effect in cadmium sulphide films after plasma treatment

In this work, the optical properties of nanocrystalline CdS films in the initial state and after ion-plasma treatment have been studied. The chemical bath deposition technique was used to prepare CdS films with thickness 80−115 nm on glass substrates. The ion-plasma treatment was carried out in argon plasma in a high-density low-pressure radio frequency inductively coupled plasma reactor at an argon ion energy of 25 eV for 30−50 s. It has been established that ion-plasma treatment leads to a decrease in film thickness by 10−15% of the initial one and the formation of new nanostructures on its surface. The results showed that the sizes of coherent scattering regions during plasma treatment decreased for a series of studied samples from 8.2−10.0 nm to 6.3−7.7 nm. This led to an increase in the band gap energy of the for nanocrystalline CdS films from 2.53−2.78 eV to 2.95−3.11 eV.