Tuning the texture and polarity of ZnO thin films deposited by spatial atomic layer deposition through the addition of a volatile shape-directing agent

Abstract

Many functional devices are nowadays based on thin films deposited by physical or chemical vapour deposition methods. Being able to control the texture of the films is very important to tune their functional properties. Texture is commonly tuned by either using single crystalline substrates or seed layers, or by modifying the deposition parameters (gas flows, precursor concentration, temperature, etc.). In this study a volatile shape-directing agent (VSDA), namely 4-(5)-Methylimidazole (4-(5)-MeIM), is used during the deposition of ZnO thin films by Atmospheric-Pressure Spatial Atomic Layer Deposition (AP-SALD) to control the texture and growth rate of the films. In particular, ZnO thin films can be grown preferentially along [001], resulting in an enhanced piezoelectric coefficient. In addition, the polarity of the ZnO films also depends on the amount of VSDA used. An innovative industry-compatible approach to control texture and polarity of ZnO thin films is presented, having a clear potential for other functional materials and applications.