A comparative study of the photoluminescence and conduction mechanisms of low temperature pulsed laser deposited and atomic layer deposited zinc oxide thin films

Abstract

Zinc oxide (ZnO) thin films were synthesized by pulsed laser deposition (PLD) and atomic layer deposition (ALD) at 100 °C on glass, and their structural, electrical, and optical properties were compared before and after 300 °C post-deposition annealing in argon, vacuum, and air. The room temperature photoluminescence (PL) of the ALD films grown at 100 °C was characterized by a broad, defect emission band peaking at 605 nm, which decreased in intensity after annealing. In contrast, the PL of the PLD films was dominated by 385 nm emission, and luminescence at 425 nm was also observed. The PL intensity of these films increased after annealing. The data suggest that overall electrical and photoluminescent characteristics of the ALD films are determined by the relative zinc interstitial and oxygen vacancy concentrations which vary with annealing treatment. The electro-optical properties of the PLD films are determined by Zn interstitials. The potential impact of the observed absorption and emission bands on optoelectronic applications is discussed. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.