Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions
Nanocrystalline zinc oxide (ZnO) with crystallite size in the range 85 -89 nm are prepared by the thermal decomposition of carbonate precursor under three different atmospheres, viz., in air ambiance, under nitrogen flow, and in vacuum. O 1s X-ray photoelectron spectra indicate that the atomic perce...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2024-06-01
|
| Series: | Chemical Physics Impact |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2667022423002955 |
| _version_ | 1797348662996631552 |
|---|---|
| author | A Mahesh G Pradeep Kumar I N Jawahar V Biju |
| author_facet | A Mahesh G Pradeep Kumar I N Jawahar V Biju |
| author_sort | A Mahesh |
| collection | DOAJ |
| description | Nanocrystalline zinc oxide (ZnO) with crystallite size in the range 85 -89 nm are prepared by the thermal decomposition of carbonate precursor under three different atmospheres, viz., in air ambiance, under nitrogen flow, and in vacuum. O 1s X-ray photoelectron spectra indicate that the atomic percentage of oxygen vacancies is more in the sample prepared under vacuum while adsorbed oxygen is more in the sample prepared in air ambience. Optical band gaps for the samples are in the range 3.17–3.20 eV. Room temperature photoluminescence spectra of the samples reveal band edge emission in the UV range (⁓3.18 eV) and broad defect mediated visible emission (⁓1.60–2.70 eV). Emission profile of excitonic emission at 80 K can be resolved into two free excitonic peaks at 3.42 eV (FX-A) and 3.46 eV (FX-B), donor bound excitonic peaks (D0X), peak due to transition of free electrons to acceptor levels (FA) donor-acceptor pair (DAP) emission and phonon replicas. D0X peak at ⁓3.35 eV has contribution from oxygen vacancies (Vo) and Zn interstitials (Zni). The most intense peak in the case of all the three samples is the FA peak at ⁓ 3.31 eV which has contribution from zinc vacancies (VZn). Temperature dependent variation of the dominant D0X and FA peaks in the range 80–400 K are analyzed using modified Varshni model which considers contributions from electron-phonon scattering and lattice thermal expansion. Defect dependent emission intensity is maximum at 80 K due to freeze-out of phonons and decreases with increase in temperature. The evolution of the colour of luminescence with temperature is studied using CIE plot method. |
| first_indexed | 2024-03-08T12:09:09Z |
| format | Article |
| id | doaj.art-dcce545aa83b48c299c8e406467017a4 |
| institution | Directory Open Access Journal |
| issn | 2667-0224 |
| language | English |
| last_indexed | 2024-03-08T12:09:09Z |
| publishDate | 2024-06-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Chemical Physics Impact |
| spelling | doaj.art-dcce545aa83b48c299c8e406467017a42024-01-23T04:16:33ZengElsevierChemical Physics Impact2667-02242024-06-018100456Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissionsA Mahesh0G Pradeep Kumar1I N Jawahar2V Biju3Department of Physics, University of Kerala, Karyavattom Campus, Thiruvananthapuram, Kerala, Pin – 695 581, IndiaDepartment of Physics, University of Kerala, Karyavattom Campus, Thiruvananthapuram, Kerala, Pin – 695 581, IndiaDepartment of Physics, University of Kerala, Karyavattom Campus, Thiruvananthapuram, Kerala, Pin – 695 581, IndiaCorresponding author.; Department of Physics, University of Kerala, Karyavattom Campus, Thiruvananthapuram, Kerala, Pin – 695 581, IndiaNanocrystalline zinc oxide (ZnO) with crystallite size in the range 85 -89 nm are prepared by the thermal decomposition of carbonate precursor under three different atmospheres, viz., in air ambiance, under nitrogen flow, and in vacuum. O 1s X-ray photoelectron spectra indicate that the atomic percentage of oxygen vacancies is more in the sample prepared under vacuum while adsorbed oxygen is more in the sample prepared in air ambience. Optical band gaps for the samples are in the range 3.17–3.20 eV. Room temperature photoluminescence spectra of the samples reveal band edge emission in the UV range (⁓3.18 eV) and broad defect mediated visible emission (⁓1.60–2.70 eV). Emission profile of excitonic emission at 80 K can be resolved into two free excitonic peaks at 3.42 eV (FX-A) and 3.46 eV (FX-B), donor bound excitonic peaks (D0X), peak due to transition of free electrons to acceptor levels (FA) donor-acceptor pair (DAP) emission and phonon replicas. D0X peak at ⁓3.35 eV has contribution from oxygen vacancies (Vo) and Zn interstitials (Zni). The most intense peak in the case of all the three samples is the FA peak at ⁓ 3.31 eV which has contribution from zinc vacancies (VZn). Temperature dependent variation of the dominant D0X and FA peaks in the range 80–400 K are analyzed using modified Varshni model which considers contributions from electron-phonon scattering and lattice thermal expansion. Defect dependent emission intensity is maximum at 80 K due to freeze-out of phonons and decreases with increase in temperature. The evolution of the colour of luminescence with temperature is studied using CIE plot method.http://www.sciencedirect.com/science/article/pii/S2667022423002955Zinc oxideTemperature dependent luminescenceExcitonmodified Varshni relationDefects |
| spellingShingle | A Mahesh G Pradeep Kumar I N Jawahar V Biju Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions Chemical Physics Impact Zinc oxide Temperature dependent luminescence Exciton modified Varshni relation Defects |
| title | Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions |
| title_full | Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions |
| title_fullStr | Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions |
| title_full_unstemmed | Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions |
| title_short | Temperature Dependent Photoluminescence Spectra of Nanocrystalline Zinc Oxide: Effect of processing condition on the excitonic and defect mediated emissions |
| title_sort | temperature dependent photoluminescence spectra of nanocrystalline zinc oxide effect of processing condition on the excitonic and defect mediated emissions |
| topic | Zinc oxide Temperature dependent luminescence Exciton modified Varshni relation Defects |
| url | http://www.sciencedirect.com/science/article/pii/S2667022423002955 |
| work_keys_str_mv | AT amahesh temperaturedependentphotoluminescencespectraofnanocrystallinezincoxideeffectofprocessingconditionontheexcitonicanddefectmediatedemissions AT gpradeepkumar temperaturedependentphotoluminescencespectraofnanocrystallinezincoxideeffectofprocessingconditionontheexcitonicanddefectmediatedemissions AT injawahar temperaturedependentphotoluminescencespectraofnanocrystallinezincoxideeffectofprocessingconditionontheexcitonicanddefectmediatedemissions AT vbiju temperaturedependentphotoluminescencespectraofnanocrystallinezincoxideeffectofprocessingconditionontheexcitonicanddefectmediatedemissions |