UV-enhanced ALD를 이용한 전도성 ZnO 박막 제조

Abstract

We fabricated the conductive zinc oxide(ZnO) thin films using UV-enhanced atomic layer deposition. ZnO is semiconductor with a wide band gap(3.37eV) and transparent in the visible region. ZnO can be deposited with various methods, such as metal organic chemical vapour deposition, magnetron sputtering and pulsed laser ablation deposition. Atomic layer deposition(ALD) is based on the sequential, saturating surface reaction, which are accomplished by alternative dosing the gaseous precursors. Due to its self-limiting growth mechanism, ALD is useful to deposit conformal and precise thin films. In this experiment, ZnO thin films was deposited by atomic layer deposition using diethylzinc(DEZ) and D.I. water(H2O) as precursors with UV irradiation. The difference from thermal ALD is that the UV light is irradiated to the substrate during H2O dosing and the additional irradiation is done after H2O dosing. As varying the UV exposure time, the resistivity of ZnO thin films changed. It was very effective to improve the conductivity of ZnO thin films. The thickness was measured by the ellipsometry and the transmittance was measured by the UV-visible spectroscope. The resistivity of ZnO thin films was investigated by the four-point probe. The chemical composition of ZnO was also investigated by X-ray photoelectron spectroscopy. From these result, it is expected that ZnO thin films deposited by UV-enhanced ALD can be applied to electronic or photonic devices as electrode and also especially used in solar cells or organic light emitting diode as the transparent electrode.