TY - JOUR
T1 - Growth of high-quality epitaxial ZnO films on (10-10) sapphire by atomic layer deposition with flow-rate interruption method
AU - Huang, Jheng Ming
AU - Ku, Ching Shun
AU - Lee, Hsin Yi
AU - Lin, Chih Ming
AU - Chen, San-Yuan
PY - 2013/9/25
Y1 - 2013/9/25
N2 - A novel process in an atomic layer deposition system with "flow-rate interruption" (FRI) was developed to obtain epitaxial ZnO films of high quality. The m-plane ZnO thin films were grown on m-plane sapphire substrates by atomic layer deposition with FRI or a conventional continuous-flow method at the temperature in the range of 25-260°C; 200°C appeared optimal. Measurements of X-ray reflectivity indicated that the thickness of ZnO films with FRI is almost twice than that grown with the continuous-flow method. The structural, optical and electrical properties were investigated with X-ray diffraction (XRD), photoluminescence and Hall measurements. The diffraction results indicated that the interrupted flow might extend the reaction of diethylzinc and water through an increased duration to improve the crystallographic quality of the films. According to the results from XRD at high resolution, to substantiate the epitaxial relation between the thin film and the substrate, an off-normal azimuthal scan along ZnO (201) demonstrated two-fold symmetry that indicated the ZnO films to be in epitaxial growth on sapphire. The photoluminescence results showed a strongly enhanced near-band-edge emission of an FRI sample, and the donor-bond exciton appearing in films also indicated superior crystalline qualities. The Hall mobility of the FRI method was up to 64.7cm2V-1s-1. The FRI method evidently improved the structural, optical and electrical properties of the ZnO films with small consumption of precursors.
AB - A novel process in an atomic layer deposition system with "flow-rate interruption" (FRI) was developed to obtain epitaxial ZnO films of high quality. The m-plane ZnO thin films were grown on m-plane sapphire substrates by atomic layer deposition with FRI or a conventional continuous-flow method at the temperature in the range of 25-260°C; 200°C appeared optimal. Measurements of X-ray reflectivity indicated that the thickness of ZnO films with FRI is almost twice than that grown with the continuous-flow method. The structural, optical and electrical properties were investigated with X-ray diffraction (XRD), photoluminescence and Hall measurements. The diffraction results indicated that the interrupted flow might extend the reaction of diethylzinc and water through an increased duration to improve the crystallographic quality of the films. According to the results from XRD at high resolution, to substantiate the epitaxial relation between the thin film and the substrate, an off-normal azimuthal scan along ZnO (201) demonstrated two-fold symmetry that indicated the ZnO films to be in epitaxial growth on sapphire. The photoluminescence results showed a strongly enhanced near-band-edge emission of an FRI sample, and the donor-bond exciton appearing in films also indicated superior crystalline qualities. The Hall mobility of the FRI method was up to 64.7cm2V-1s-1. The FRI method evidently improved the structural, optical and electrical properties of the ZnO films with small consumption of precursors.
KW - Atomic-layer deposition
KW - Flow-rate interruption
KW - X-ray diffraction
KW - ZnO
UR - http://www.scopus.com/inward/record.url?scp=84882864193&partnerID=8YFLogxK
U2 - 10.1016/j.surfcoat.2012.05.067
DO - 10.1016/j.surfcoat.2012.05.067
M3 - Article
AN - SCOPUS:84882864193
SN - 0257-8972
VL - 231
SP - 323
EP - 327
JO - Surface and Coatings Technology
JF - Surface and Coatings Technology
ER -