Nanoscale surface electrical properties of aluminum zinc oxide thin films investigated by scanning probe microscopy

Conducting atomic force microscopy and scanning surface potential microscopy were adopted to study the nanoscale surface electrical properties of aluminum zinc oxide (AZO) films that were prepared by pulsed laser deposition (PLD) at various substrate temperatures for use as anode materials in polymer light-emitting diodes (PLEDs). Experimental results indicate that when substrate temperatures exceed 100 degrees C, the local conductivity and work function are positively correlated with the concentrations of Al dopant and O(2-) on AZO surface. When the substrate temperature is approximately 150 degrees C, the percentage coverage of conducting regions of the AZO surface and the mean work function are 90.20% and 4.85 eV, respectively. Additionally, both microcosmic uniformities meet the standard applied to PLEDs. This low-temperature condition for PLD significantly reduces the yield rate of impurities when AZO vacuum evaporation is performed on a plastic substrate, supporting various applications of AZO films. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3042237]