Luminescence behavior and compensation effect on the hole concentration in the sol-gel Zn1−xCuxSy films with different compositions

This study determines the effect of Cu and S content on the structural, luminescence and electrical properties of sol-gel Zn1−xCuxSy films. The dependence of acceptors [interstitial sulfur (Si)] and donors [sulfur vacancy (VS)] on the film composition allows the hole concentration of Zn1−xCuxSy samples to be tuned. It is found that an increased Cu/Zn molar ratio leads to a reduced probability of the formation of VS, which increases the hole concentration. An increase in Cu/Zn and S/Zn molar ratios leads to a significantly increased probability of the formation of Si and a reduced probability of the formation of VS, which significantly increases the hole concentration. Clearly, compensation effects limit the hole concentration of Zn1−xCuxSy samples. The results show that Si is the origin of the p-type conductivity. It is also shown that a suitable choice of composition increases acceptor-like defect formation in Zn1−xCuxSy.