Thermally activated below-band-gap excitation behind green photoluminescence in ZnO

Kodama, Kanako; Uchino, Takashi

doi:10.1063/1.4712624

Cited by 41 publications

(41 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…49 We have also concluded from Eq. (2) that the confocal volume wherein the atoms are being probed via CPL measurements can extend several hundreds of nanometers below the surface, where the effect of surface band bending is absent and the ionization of V O is negligible.…”

Section: A Structural Characterization Of the Zno Nw Arraysmentioning

confidence: 66%

Spatial distribution of neutral oxygen vacancies on ZnO nanowire surfaces: An investigation combining confocal microscopy and first principles calculations

Wong

Alay-e-Abbas

Fang

et al. 2013

Journal of Applied Physics

238

View full text Add to dashboard Cite

A qualitative approach using room-temperature confocal microscopy is employed to investigate the spatial distribution of shallow and deep oxygen vacancy (VO) concentrations on the polar (0001) and non-polar (101¯0) surfaces of zinc oxide (ZnO) nanowires (NWs). Using the spectral intensity variation of the confocal photoluminescence of the green emission at different spatial locations on the surface, the VO concentrations of an individual ZnO NW can be obtained. The green emission at different spatial locations on the ZnO NW polar (0001) and non-polar (101¯0) surfaces is found to have maximum intensity near the NW edges, decreasing to a minimum near the NW center. First-principles calculations using simple supercell-slab (SS) models are employed to approximate/model the defects on the ZnO NW (101¯0) and (0001) surfaces. These calculations give increased insight into the physical mechanism behind the green emission spectral intensity and the characteristics of an individual ZnO NW. The highly accurate density functional theory (DFT)-based full-potential linearized augmented plane-wave plus local orbitals (FP-LAPW + lo) method is used to compute the defect formation energy (DFE) of the SSs. Previously, using these SS models, it was demonstrated through the FP-LAPW + lo method that in the presence of oxygen vacancies at the (0001) surface, the phase transformation of the SSs in the graphite-like structure to the wurtzite lattice structure will occur even if the thickness of the graphite-like SSs are equal to or less than 4 atomic graphite-like layers [Wong et al., J. Appl. Phys. 113, 014304 (2013)]. The spatial profile of the neutral VO DFEs from the DFT calculations along the ZnO [0001] and [101¯0] directions is found to reasonably explain the spatial profile of the measured confocal luminescence intensity on these surfaces, leading to the conclusion that the green emission spectra of the NWs likely originate from neutral oxygen vacancies. Another significant result is that the variation in the calculated DFE along the ZnO [0001] and [101¯0] directions shows different behaviors owing to the non-polar and polar nature of these SSs. These results are important for tuning and understanding the variations in the optical response of ZnO NW-based devices in different geometric configurations.

show abstract

Section: A Structural Characterization Of the Zno Nw Arraysmentioning

confidence: 66%

Spatial distribution of neutral oxygen vacancies on ZnO nanowire surfaces: An investigation combining confocal microscopy and first principles calculations

Wong

Alay-e-Abbas

Fang

et al. 2013

Journal of Applied Physics

238

View full text Add to dashboard Cite

show abstract

“…Модель электронной рекомбинации на кислородных вакансиях рассмотрена для наноигл [15], тонких пленок [17,32] и поликристаллов [33,34] (рис. 1, b).…”

Section: физические механизмы и точечные дефекты ответственные за люunclassified

“…Кроме того, V 0 O -центры являются аналогом F-центров, которые хорошо изучены в ионных кристаллах CaO, SrO, BaO и MgO [37]. Модель триплет-синглетных переходов V 0 O -центров для объяснения ЗЛ находит теоретические [38] и экспериментальные [33,39] подтверждения. Считается, что в рассматриваемом процессе может также участвовать межузельный цинк Zn i (рис.…”

Section: физические механизмы и точечные дефекты ответственные за люunclassified

“…Считается, что в рассматриваемом процессе может также участвовать межузельный цинк Zn i (рис. 1, с) [33].…”

Section: физические механизмы и точечные дефекты ответственные за люunclassified

“…Показано, что механизмы возбуждения ЗЛ различаются для энергий падающих фотов, меньших (hν < E g ) и больших (hν > E g ) ширины запрещенной зоны. В первом случае осуществляется прямое возбуждение V O -центров и взаимодействие с мелкими донорами, во втором участвуют электроны зоны проводимости, которые переходят на возбужденные триплетные уровни V O -центров[33,34]. Установлено, что отжиг порошка…”

unclassified

See 2 more Smart Citations