Tailoring the Optical Properties of Zinc Oxide via Bismuth Doping and Codoping Strategies: From Birefringence to Metallicity
Energy Materials Laboratory
The Journal of Physical Chemistry C
Density functional theory was employed to explore the effect of Bi as a high-index dopant on the optical properties of titanium dioxide (TiO2), zirconium dioxide (ZrO2), and zinc oxide (ZnO). It was found that BiMetal substitutional doping results in a reduction of the band gap energy (Eg) by creating new defect states in all investigated oxides. In the case of ZnO, the in-plane refractive index (nx,y) is doubled (>3) over a wide band in mid- and far-IR regions, and the largest birefringence is observed compared to other materials reported in the literature. The presence of oxygen vacancies (Ov) was found to lower the optical losses, as evident by the decreased absorption cross section of a 250 nm radius sphere as revealed via the FDTD simulation. At 12% Bi doping, metallicity is obtained with optical losses lower than silver, gold, and transition-metal nitrides. Codoping with Bi and interstitial hydrogen (Hi) or substitutional aluminum (AlZn) showed the same effect, which increases both the in-plane and out-of-plane indices even higher but at the expense of increasing the optical losses.
Samar M. Fawzy, Yehea I. Ismail, Nageh K. Allam, "Tailoring the Optical Properties of Zinc Oxide via Bismuth Doping and Codoping Strategies: From Birefringence to Metallicity", The Journal of Physical Chemistry C 2022 126 (40), 17434-17440 DOI: 10.1021/acs.jpcc.2c05591