CHARACTERIZATION OF PULSED LASER DEPOSITED ZNO FILMS: INFLUENCE OF LASER AND BEAM PROFILE AT 532 AND 1064 NM

Abstract

ZnO thin films have been elaborated using a pulsed laser deposition (PLD) technique onto glass substrate at room temperature. The PLD process is developed in oxygen atmosphere (1*10-1 mbar). The morphology, chemical composition and optical characteristics were studied as function of laser wavelength and laser profile (532 and 1064 nm). Film properties are strongly influenced by the Gaussian profile to flat top shaped laser beam at 532 nm and 1064 nm. At regardless of laser wavelength, films prepared with flat top profile exhibit smooth surface and preferential growth direction (101), it is detected reduction of the density defects like interstitial or vacancies atoms. The optical band gap, the ratio intensity visible/UV fluorescence and peak position are modified in agree with the degradation of film stoichiometry. At regardless of the laser wavelength, the use of Gaussian beam stimulates the highest deposition rate; the surface roughness and clusters density are incremented. Films show a polycrystalline structure (100, 002 and 101). The optical band gap is modified, film stoichiometry is higher than flat top films, in agree with the fluorescence measurements. We demonstrated a simple, fast and low cost setup to elaborate ZnO films with tailored properties. These films could be used to applications in short wavelength optoelectronic devices, optical or electric sensors, also for the elaboration of nanowires using different types of substrates.

ZnO thin films have been elaborated using a pulsed laser deposition (PLD) technique onto glass substrate at room temperature. The PLD process is developed in oxygen atmosphere (1*10-1 mbar). The morphology, chemical composition and optical characteristics were studied as function of laser wavelength and laser profile (532 and 1064 nm). Film properties are strongly influenced by the Gaussian profile to flat top shaped laser beam at 532 nm and 1064 nm. At regardless of laser wavelength, films prepared with flat top profile exhibit smooth surface and preferential growth direction (101), it is detected reduction of the density defects like interstitial or vacancies atoms. The optical band gap, the ratio intensity visible/UV fluorescence and peak position are modified in agree with the degradation of film stoichiometry. At regardless of the laser wavelength, the use of Gaussian beam stimulates the highest deposition rate; the surface roughness and clusters density are incremented. Films show a polycrystalline structure (100, 002 and 101). The optical band gap is modified, film stoichiometry is higher than flat top films, in agree with the fluorescence measurements. We demonstrated a simple, fast and low cost setup to elaborate ZnO films with tailored properties. These films could be used to applications in short wavelength optoelectronic devices, optical or electric sensors, also for the elaboration of nanowires using different types of substrates.