The impact on in-situ-hydrogen-plasma treatment for zinc oxide plasma enhanced atomic layer deposition

Abstract

ZnO films were deposited by the PEALD using oxygen and hydrogen plasmas at 100 degrees C. As the oxygen plasma increased by 200 W, the growth rate saturated to 1.78 angstrom/cycle over 150 W. The film resistivity increased to 4.95 x 10(3) Omega cm without a significant change of film crystallinity but the carrier concentration drastically decreased to 4.87 x 10(13) cm(-3) as the oxygen plasma power increased to 200 W. Interestingly, as the hydrogen plasma power increased during ZnO PEALD (DEZ + O-2 plasma + H-2 plasma), the growth rate, film crystallinity and resistivity drastically decreased. Although the crystallinity of z-axis ZnO film decreased, the ZnO film exhibited the conducting property. Based on x-ray photoelectron spectroscopy and auger electron spectroscopy analysis, the higher oxygen plasma power may help to decrease oxygen vacancies but the higher hydrogen plasma power can induce in generation oxygen vacancies and hydroxyl groups in ZnO films, strongly relating with the changes of carrier concentrations. The hydrogen and oxygen plasma exhibited conflicting behaviors in terms of ZnO electrical property. Thus, the electrical properties on ZnO film PEALD are easily manipulated even on very low deposition temperature, with only selecting oxygen and hydrogen plasma conditions. (C) 2012 Elsevier B.V. All rights reserved.