Effect of substrate-induced strain on the morphological, electrical, optical and photoconductive properties of RF magnetron sputtered ZnO thin films

ZnO thin films have been grown by radio frequency (RF) magnetron sputtering on different substrates such as glass, quartz (z-cut), sapphire (0 0 1) and Si (1 0 0) in order to study the effect of substrate-induced strain along c-axis on the structural, electrical, optical and photoconducting properties of the films. The full width at half maximum for (0 0 0 2) peak increases while the crystallite size decreases with decrease in the compressive strain. The change in resistivity and carrier concentration has been related to the variation of strain. The resistivity of the films increases and the carrier concentration decreases exponentially with increasing the strain. The film on the quartz substrate shows higher UV emission intensity. The ultraviolet photosensitivity decreases with increase in the strain.