Fabrication of pulsed laser-deposited Cr-doped zinc oxide thin films: structural, morphological, and optical studies

High-quality c-axis-oriented Cr-doped ZnO thin films were grown on 100-μm-thick Si (100) wafer substrate by Pulsed Laser Deposition (PLD) technique. The PLD is a versatile technique for growing thin films and a wide range of materials. The structural analyses confirm the wurtzite structure of synthesized samples and are preferentially oriented along c-axis perpendicular to substrate the surface. The intensity of defect-induced mode frequency for Cr-doped ZnO film increased due to the formation of highly crystalline films. In Raman spectra, E₂ (high) mode shows redshift owing to optical phonon confinement induced by uncertainty in photon wave vectors i.e., downshift of Raman peaks. Cr-doped ZnO thin film consists of nanorod-shaped grains of different sizes. Each rod possesses width in a range of 85–93 nm and length upto several hundred nanometres. The decrease in peak intensity of Cr-doped ZnO film photoluminescence (PL) spectrum is attributed to a fall in the electron–hole recombination process. In visible region of PL spectra, green light emission peak at about 567 nm was associated with defects in ZnO. It is observed after doping root mean square (RMS) roughness increases with which means the surfaces becomes rough and grain size increases.