Blue luminescence from ZnGa 2 O 4 : Effect of lattice distortion and particle size

Kamal, Chirauri. Satya; Naidu, B. S.; Vishwanadh, B.; Rao, K. Ramachandra; Sudarsan, V.; Ramachandra, R.K.

doi:10.1016/j.jlumin.2017.04.056

Cited by 32 publications

(6 citation statements)

References 28 publications

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“…The calculated defect formation energies are found to be higher in comparison to the other intrinsic defects, indicating a relatively lower population of interstitial defects (Figure a). This is consistent with the experimental observation of the dominance of antisite and vacancy defects over interstitial defects. − Figure h,i shows the density of states for the ZnGa 2 O 4 in the presence of Ga i and Zn i , respectively. In the case of Ga i , the impurity states appear 1.23 eV below the CBM, resulting in a reduction in the effective band gap to 2.60 eV.…”

Section: Results and Discussionsupporting

confidence: 88%

“…Therefore, two emissions are often observed in pure ZnGa 2 O 4 due to the coupling of defect traps and electronic levels from Ga–O groups . The emissions have been ascribed to the distorted [GaO 6 ] and [GaO 4 ] structural units with oxygen vacancies by other groups. , However, because of the large band gap normal ZnGa 2 O 4 phase, it hardly responds in the visible spectrum, leading to a poor persistent luminescence property. Therefore, color tuning in the desired range has been achieved by doping or codoping with suitable metal elements.…”

Section: Introductionmentioning

confidence: 99%

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Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study

Modak

2023

J. Phys. Chem. C

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Wide band gap semiconductors with high dielectric constant and good thermal dissipation are very popular for a wide range of optical and electronic devices. In recent studies, ZnGa2O4 has been projected as an alternative to Ga2O3. The structural simplicity (face-centered-cubic spinel structure) results in isotropic electronic and optical properties for ZnGa2O4 in comparison to the large anisotropic properties for the β-monoclinic variety of Ga2O3. Motivated by recent experimental observations on the enhancement of optical properties of ZnGa2O4 due to doping with Ge, the author has carried out a detailed systematic calculation using density functional theory to find out the origin. The present study investigates the structure, formation energies, and electronic properties of different intrinsic vacancy defects in Ge-doped ZnGa2O4 under various growth conditions. The doping of Ge is found to be energetically favored at both the tetrahedral sites and octahedral sites under oxygen-rich conditions. It has been revealed that the optical behavior of the undoped ZnGa2O4 is attributed to the electron trap centers induced by oxygen vacancy and hole trap centers induced by gallium vacancy, zinc vacancy, and antisite defect. Interestingly, the relative population of these intrinsic defects changed in the presence of Ge. It has been observed that antisite defects are no longer dominating defects in the presence of Ge. More interestingly, gallium vacancy, which is the dominating defect in the presence of Ge, can reduce the band gap significantly without introducing localized midgap states, which is very much important for achieving enhanced efficiency. Thus, the present study will be helpful for understanding the effects of native point defects and external Ge doping on ZnGa2O4 and provides important guidelines to design its band gap with the desired range by tuning the synthesis conditions.

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Section: Results and Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study

Modak

2023

J. Phys. Chem. C

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“…Researchers have discussed many one-dimensional (1D) ZnGa 2 O 4 nanostructures (nanoparticles, nanocrystal, nanowires, and nanotube) over the years [7][8][9]. Although these 1D ZnGa 2 O 4 devices exhibit high optoelectronic performance, the reliability and stability of these devices are a critical aspect of their application, which raises concern [10,11].…”

Section: Introductionmentioning

confidence: 99%

Influence of Annealing Temperature on the Properties of ZnGa2O4 Thin Films by Magnetron Sputtering

et al. 2019

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Zinc gallate (ZnGa2O4) thin films were grown on sapphire (0001) substrate using radio frequency (RF) magnetron sputtering. After the thin film deposition process, the grown ZnGa2O4 was annealed at a temperature ranging from 500 to 900 °C at atmospheric conditions. The average crystallite size of the grown ZnGa2O4 thin films increased from 11.94 to 27.05 nm as the annealing temperature rose from 500 to 900 °C. Excess Ga released from ZnGa2O4 during thermal annealing treatment resulted in the appearance of a Ga2O3 phase. High-resolution transmission electron microscope image analysis revealed that the preferential crystallographic orientation of the well-arranged, quasi-single-crystalline ZnGa2O4 (111) plane lattice fringes were formed after the thermal annealing process. The effect of crystallite sizes and lattice strain on the width of the X-ray diffraction peak of the annealed ZnGa2O4 thin films were investigated using Williamson-Hall analysis. The results indicate that the crystalline quality of the deposited ZnGa2O4 thin film improved at higher annealing temperatures.

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“…Optoelectronic devices fabricated with one-dimensional nanostructures, such as nanotubes, nanowires, and nanocrystals, can achieve a high photoelectric conversion efficiency. However, in practice their stability and repeatability are still major concerns [16][17][18]. Hence, the development of ZnGa 2 O 4 film-based PDs is essential.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Annealing Ambience on the Material and Photodetector Characteristics of Sputtered ZnGa2O4 Films

et al. 2021

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Spinel ZnGa2O4 films were grown on c-plane sapphire substrates at the substrate temperature of 400 °C by radio-frequency magnetron sputtering. Post thermal annealing was employed at the annealing temperature of 700 °C in order to enhance their crystal quality. The effect of thermal annealing on the microstructural and optoelectronic properties of ZnGa2O4 films was systematically investigated in various ambiences, such as air, nitrogen, and oxygen. The X-ray diffraction patterns of annealed ZnGa2O4 films showed the crystalline structure to have (111) crystallographic planes. Transmission electron micrographs verified that ZnGa2O4 film annealed under air ambience possesses a quasi-single-crystalline structure. This ZnGa2O4 film annealed under air ambience exhibited a smooth surface, an excellent average transmittance above 82% in the visible region, and a wide bandgap of 5.05 eV. The oxygen vacancies under different annealing ambiences were revealed a substantial impact on the material and photodetector characteristics by X-ray photoelectron spectrum investigations. ZnGa2O4 film exhibits optimal performance as a metal-semiconductor-metal photodetector when annealed under air ambience. Under these conditions, ZnGa2O4 film exhibits a higher photo/dark current ratio of ~104 order, as well as a high responsivity of 2.53 A/W at the bias of 5 V under an incident optical light of 240 nm. These results demonstrate that quasi-single-crystalline ZnGa2O4 films have significant potential in deep-ultraviolet applications.

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Blue luminescence from ZnGa 2 O 4 : Effect of lattice distortion and particle size

Cited by 32 publications

References 28 publications

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study

Influence of Annealing Temperature on the Properties of ZnGa2O4 Thin Films by Magnetron Sputtering

The Effect of Annealing Ambience on the Material and Photodetector Characteristics of Sputtered ZnGa2O4 Films

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Blue luminescence from ZnGa 2 O 4 : Effect of lattice distortion and particle size

Cited by 32 publications

References 28 publications

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa2O4: Insights from a DFT Study

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa2O4: Insights from a DFT Study

Influence of Annealing Temperature on the Properties of ZnGa2O4 Thin Films by Magnetron Sputtering

The Effect of Annealing Ambience on the Material and Photodetector Characteristics of Sputtered ZnGa2O4 Films

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Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study

Energetic, Electronic, and Optical Behavior of Intrinsic Charge Carrier-Trapping Defects in Ge-Doped ZnGa₂O₄: Insights from a DFT Study