Impact of local arrangement of Mg and Zn atoms in rocksalt-structured MgxZn1−xO alloys on bandgap and deep UV cathodoluminescence peak energies

Observation of deep ultraviolet (UV) cathodoluminescence peaks around 4.88–5.86 eV and optical transmittance measurements in the far UV spectral range enabled us to find a relatively large Stokes-like shift of 0.7–0.8 eV in rocksalt-structured (RS) MgxZn1−xO films with x = 0.61–0.92 grown on (001) MgO substrates by using the mist chemical vapor deposition method. Electronic structure calculations suggested the existence of bandgap energy (Eg) fluctuations induced by differences in the local arrangement of Mg and Zn atoms in the RS-MgxZn1−xO alloy. The Eg fluctuations and resultant exciton localization were determined to be possible origins of the large Stokes-like shift.Observation of deep ultraviolet (UV) cathodoluminescence peaks around 4.88–5.86 eV and optical transmittance measurements in the far UV spectral range enabled us to find a relatively large Stokes-like shift of 0.7–0.8 eV in rocksalt-structured (RS) MgxZn1−xO films with x = 0.61–0.92 grown on (001) MgO substrates by using the mist chemical vapor deposition method. Electronic structure calculations suggested the existence of bandgap energy (Eg) fluctuations induced by differences in the local arrangement of Mg and Zn atoms in the RS-MgxZn1−xO alloy. The Eg fluctuations and resultant exciton localization were determined to be possible origins of the large Stokes-like shift.

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