Effects of high temperature annealing on defects and luminescence properties in H implanted ZnO

Chan, Keng Siew; Vines, Lasse; Choi, Sumin; Phillips, M. R.; Svensson, B. G.; Jagadish, Chennupati; Wong‐Leung, Jennifer

doi:10.1088/0022-3727/47/34/342001

Cited by 9 publications

(3 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chen et al also identified [17] the clustering of several (4-6) V Zn -V O divacancies from the measured value of PAL in Al irradiated ZnO. The agglomeration of V Zn and V O defects (in general (V Zn ) m -(V O ) n type with m ≈ n) during annealing (at a relatively lower temper ature [23]) or by multiple collision cascades of energetic ions may lead to nano-voids in the system [24,25]. From the surface energy consideration, if two open volume defects with similar radii coalesce to form a larger one, energy is lowered roughly by 20%.…”

Section: Introductionmentioning

confidence: 99%

Clustered vacancies in ZnO: chemical aspects and consequences on physical properties

Pal¹,

Gogurla²,

Das³

et al. 2018

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

Chemical nature of point defects, their segregation, cluster or complex formation in ZnO is an important area of investigation. In this report, 1.2 MeV Ar ion beam is used to incorporate defects in granular ZnO. Evolution of defective state with irradiation fluence 1 × 10 14 and 1 × 10 16 ions/cm 2 has been monitored using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and Raman spectroscopic study. Choice of such fluence regime ensures spatial overlapping of successive ion-target collision cascades so that reorganization of point defects can take place in the form of more stable clusters or in the direction of possible recovery. XPS study shows presence of oxygen vacancies (VO) in the Ar ion irradiated ZnO. Zn(LMM) Auger spectra clearly identifies transition involving metallic zinc in the irradiated samples. Intense PL emission from interstitial Zn (IZn) related shallow donor bound excitons (DBX) is visible in the 10 K spectra for all samples. Although overall PL is largely reduced with irradiation disorder, DBX intensity is increased for the highest fluence irradiated sample. Raman study indicates damage in both zinc and oxygen sub-lattice by energetic ion beam. Representative Raman modes from defect complexes involving VO, IZn and IO are visible after irradiation with intermediate fluence. Further increase of fluence shows, to some extent, a homogenization of disorder. Huge reduction of resistance is also noted for this sample. Certainly, high irradiation fluence induces a qualitative modification of the conventional (and highly resistive) grain boundary (GB) structure of granular ZnO. Low resistive path, involving IZn related shallow donors, across the GB can be presumed to explain resistance reduction. Open volumes (VZn and VO) agglomerate more and more with increasing irradiation fluence and finally get transformed to voids. Results as a whole have been elucidated with a model which emphasizes possible evolution of new defect microstructure that is distinctively different from the GB related disorder. Based on the model, qualitative explanations of commonly observed radiation hardness, colouration and 3 ferromagnetism in disordered ZnO have been put forward. A coherent scenario on disorderaccumulation in ZnO has been presented, which we believe, will guide further discussion on this topic.

show abstract

Section: Introductionmentioning

confidence: 99%

Clustered vacancies in ZnO: chemical aspects and consequences on physical properties

Pal¹,

Gogurla²,

Das³

et al. 2018

J. Phys. D: Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…It is known that the structural, optical, and electrical properties of ZnO materials can be modified by doping them with the heterovalent impurities. For instance, the implantation of singlevalence ions (H + , Li + , and Cu + ) induces blue and green emission bands in the ZnO-based materials [27][28][29]. It is interesting that doping with Li + can also affect the ZnO sample structure.…”

Section: Introductionmentioning

confidence: 99%

Effects of thermal treatment on the complex structure of luminescence emission of Li-doped ZnO screen-printed films

Chukova,

Borkovska,

Khomenkova

et al. 2023

Front. Phys.

View full text Add to dashboard Cite

The ZnO–Li films were synthesized and investigated in an attempt to explore and develop RE-free phosphor materials capable of emitting intense visible light in a wide spectral range. The effects of both heterovalent doping with lithium and high-temperature annealing on the optical properties of ZnO films were studied. The films were deposited on the Al2O3 substrate using the screen-printing method and annealed at 800–1,000°C in air for 0.5–3 h. Both doping and annealing result in the transformation of the shape of reflectance spectra in the range of 300–400 nm and the shift of absorption edge to the long-wavelength region. At the same time, the bandgap value estimated taking into account the exciton peak position and its binding energy is independent of Li-doping. The feature at 300–400 nm and the shift of absorption edge are ascribed to the appearance of the absorption band that excited the yellow photoluminescence band. The photoluminescence spectra of undoped and Li-doped films show the emission bands in the ultraviolet and visible spectral ranges. The ultraviolet emission is due to ZnO exciton recombination. The visible emission band comprises several components peaked at 430, 482, 540, 575, and 640 nm. Their relative intensities depend on Li-doping, annealing temperature, and annealing duration. The 430- and 482-nm luminescence bands were observed in Li-doped films only. Their excitation spectra show the peak located at 330–340 nm, indicating that the energy significantly exceeds the ZnO bandgap energy. Consequently, the 430- and 482-nm luminescence bands are attributed to an additional crystal phase formed under annealing. Other components of visible emission bands are ascribed to the defect-related emission of ZnO. The possible nature of these bands is further discussed. Li-doping and annealing at intermediate temperatures result in blue emission and an enhancement of other visible bands, which makes ZnO–Li films a perspective material in photonic applications.

show abstract

“…The GL‐S band has a zero phonon line (ZPL) at ≈2.86 eV and is visible usually at temperatures below ≈100 K, mainly in the samples that underwent a high‐temperature growth [ 11,12 ] or an annealing in O 2 or air (>600 °C). [ 13–18 ] In comparison with the GL‐S band, the structureless GL band can be observed in most samples from room temperature down to 1.8 K, [ 1,9 ] whereas no definite ZPL has been reported. If not considering the fine structure, the structureless GL band is analogous to the GL‐S band in the spectral shape except for a shift of ≈0.05 eV (≈10 nm) toward the high‐energy side with respect to the GL‐S band.…”

Section: Introductionmentioning

confidence: 99%

Effects of Surface States on the Green Luminescence in ZnO

Zhou

Zhang

et al. 2021

Physica Status Solidi (b)

View full text Add to dashboard Cite

The origin of green luminescence (GL) band is an issue long‐term pending in the research of ZnO. Herein, three GL bands (GL1, GL2, and GL‐S bands) are unambiguously identified using the single‐crystal samples with and without a SiOx passivation layer and the polycrystal samples annealed in H2 and O2 atmospheres. Solid evidence demonstrates that the GL1 band can be assigned to the optical emissions from the sample inside and the intensity is decreased with the decrease in temperature. The GL2 and GL‐S bands, which correspond to the structureless and structured GL bands of H‐ and O‐annealed samples, respectively, are found to come from the sample surface and enhanced at low temperatures. Excitons or free electrons and holes generated through interband absorption are found to play an important role in exciting both the GL2 and GL‐S bands. For the light with photon energy lower than the bandgap, however, the GL‐S and GL2 bands exhibit different excitation behaviors. The deficiency of oxygen on the sample surface is confirmed to be the reason resulting in the GL2 band and probably also the reason leading to the GL‐S band.

show abstract

Effects of high temperature annealing on defects and luminescence properties in H implanted ZnO

Cited by 9 publications

References 33 publications

Clustered vacancies in ZnO: chemical aspects and consequences on physical properties

Clustered vacancies in ZnO: chemical aspects and consequences on physical properties

Effects of thermal treatment on the complex structure of luminescence emission of Li-doped ZnO screen-printed films

Effects of Surface States on the Green Luminescence in ZnO

Contact Info

Product

Resources

About