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APCVD of ZnO: Al, insight and control by modeling

Author: Deelen, J. van · Illiberi, A. · Kniknie, B.J. · Steijvers, H.L.A.H. · Lankhorst, A.M. · Simons, P.J.P.M.
Type:article
Date:2013
Publisher: Elsevier
Place: Amsterdam
Institution: TNO, Dept. Thin Film Technology, De Rondom 1, 5612 AP Eindhoven, Netherlands Celsian Glass and Solar B.V., De Rondom 1, 5612 AP Eindhoven, Netherlands
Source:Surface and Coatings Technology, 230, 239-244
Identifier: 478185
Keywords: Materials · APCVD · Transparent conductors · Zinc oxide · ZnO · Atmospheric pressure · Chemical vapor deposition · CVD · Deposition temperatures · Increasing temperatures · Industrial reactors · Transparent conductors · Reaction intermediates · Surface reactions · High Tech Systems & Materials · Industrial Innovation · Mechatronics, Mechanics & Materials · TFT - Thin Film Technology · TS - Technical Sciences

Abstract

Atmospheric pressure chemical vapor deposition (APCVD) of ZnO from diethyl zinc (DEZn) and t-butanol was performed using an industrial reactor design. Deposition profiles were recorded to gain insight in the position dependent variations in layer thickness in such a reactor. We observed that for a deposition temperature below 400 °C most of the deposition took place close to the exit of the gasses, while for increasing temperatures the deposition shifts towards the gas inlet. This trend can be explained by the reaction mechanism through an intermediate alkoxide species from DEZn and t-butanol, which in turn leads to ZnO deposition through a surface reaction. The deposition profile is dependent on the local alkoxide concentration. With increasing temperature, the formation rate increases. This translates in an earlier formation, i.e. in a shift upstream towards gas inlet because this alkoxide formation takes place during the transport through the reactor. Chemical vapor deposition (CVD) is a highly complex system with many interacting physical and chemical processes. Modeling was used to gain insight on the local variations of the concentration of reactive species inside a reactor and was shown to predict the deposition profiles. Moreover, the impact of changes in reactor design on the deposition is discussed. © 2013 Elsevier B.V.