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Tunable Direct Band Gap of β‑CuGaO2 and β‑LiGaO2 Solid Solutions in the Full Visible Range
journal contribution
posted on 2019-03-15, 16:04 authored by Issei Suzuki, Yuki Mizuno, Takahisa OmataWe
synthesized solid solutions of β-CuGaO2 and β-LiGaO2 (i.e., β-(Cu1–xLix)GaO2) by partial
ion exchange of Cu+ in β-CuGaO2 with Li+ from LiCl in the composition range of 0 ≤ x ≤ 0.89. The energy band gap of β-CuGaO2 (1.47 eV) increased linearly up to 3.0 eV with increasing
Li content, covering the full visible range. The crystal structures
of the solid solutions were analyzed using the Rietveld method. The
structural distortions of the solid solutions with respect to the
ideal binary wurtzite-type structure were relatively small because
of the similar ionic radii of Li+, Cu+, and
Ga3+. Based on a recently proposed hypothesis relating
structural distortion to the nature of the band gap (i.e., direct
or indirect), it is expected that the solid solution has a direct
band gap. We anticipate that this solid solution system will contribute
to the realization of oxide-based optoelectronic devices.