Effects of substrate temperature on the Ga-doped ZnO films as an anode material of organic light emitting diodes

Abstract

We investigated the transparent electrode properties of Ga-doped (3.0 at.%) zinc oxide (GZO) films deposited by pulsed DC magnetron sputtering and the device performance of organic light emitting diodes (OLEDs) using GZO as an anode layer. The structural, electrical, and optical properties of the GZO films, which are deposited at different substrate temperatures, are examined with various analysis including X-ray diffraction, Hall measurement, and UV–visible spectrometer. The GZO film was grown with a highly c-axis orientation perpendicular to the substrate at the 300°C. The crystallinity of the GZO film significantly affected its electrical and optical properties. The physical properties of the GZO film deposited at 300°C exhibited the best results, such as a low resistivity of 4.3×10−4Ωcm, high carrier concentration of 6.3×1020cm−3 and mobility of 23.0cm2/Vs. The performance of OLEDs device with a GZO anode film deposited at optimum temperature condition showed excellent brightness >10,000cd/m2 owing to its low sheet resistance and high optical transmittance. These results suggest that GZO film can be promising candidate as the anode layer in OLEDs as a substitution to ITO film.