Stochastic inhomogeneous oxidation is an inherent characteristic of copper (Cu), often hindering color tuning and bandgap engineering of oxides. Coherent control of the interface between metal and metal oxide remains unresolved. Coherent propagation of an oxidation front in single-crystal Cu thin film is demonstrated to achieve a full-color spectrum for Cu by precisely controlling its oxide-layer thickness. Grain-boundary-free and atomically flat films prepared by atomic-sputtering epitaxy allow tailoring of the oxide layer with an abrupt interface via heat treatment with a suppressed temperature gradient. Color tuning of nearly full-color red/green/blue indices is realized by precise control of the oxide-layer thickness; the samples cover ≈50.4% of the standard red/green/blue color space. The color of copper/copper oxide is realized by the reconstruction of the quantitative yield color from the oxide “pigment” (complex dielectric functions of Cu2O) and light-layer interference (reflectance spectra obtained from the Fresnel equations) to produce structural color. Furthermore, laser-oxide lithography is demonstrated with micrometer-scale linewidth and depth through local phase transformation to oxides embedded in the metal, providing spacing necessary for semiconducting transport and optoelectronics functionality.
|Publication status||Published - 2021 Apr 15|
Bibliographical noteFunding Information:
S.J.K., S.K., and J.L. contributed equally to this work. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the MSIT (Grant Numbers. NRF-2017R1A2B3011822, NRF-2020R1A4A4078780, NRF-2019R1A2B5B02004546, NRF-2019R1C1C1011180, and NRF-2019R1A2C1005267) and Institute for Basic Science (IBS-R011-D1). Spectroscopic ellipsometry has been performed using facilities at IBS Center for Correlated Electron Systems, Seoul National University. The single-crystal target was supplied by the Crystal Bank Research Institute of Pusan National University, Korea.
© 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering