1
|
Al Fattah MF, Amin MR, Mallmann M, Kasap S, Schnick W, Moewes A. Electronic structure investigation of wide band gap semiconductors-Mg 2PN 3and Zn 2PN 3: experiment and theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:405504. [PMID: 32364135 DOI: 10.1088/1361-648x/ab8f8a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
The research on nitridophosphate materials has gained significant attention in recent years due to the abundance of elements like Mg, Zn, P, and N. We present a detailed study of band gap and electronic structure of M2PN3(M = Mg, Zn), using synchrotron-based soft x-ray spectroscopy measurements as well as density functional theory (DFT) calculations. The experimental N K-edge x-ray emission spectroscopy (XES) and x-ray absorption spectroscopy (XAS) spectra are used to estimate the band gaps, which are compared with our calculations along with the values available in literature. The band gap, which is essential for electronic device applications, is experimentally determined for the first time to be 5.3 ± 0.2 eV and 4.2 ± 0.2 eV for Mg2PN3and Zn2PN3, respectively. The experimental band gaps agree well with our calculated band gaps of 5.4 eV for Mg2PN3and 3.9 eV for Zn2PN3, using the modified Becke-Johnson (mBJ) exchange potential. The states that contribute to the band gap are investigated with the calculated density of states especially with respect to two non-equivalent N sites in the structure. The calculations and the measurements predict that both materials have an indirect band gap. The wide band gap of M2PN3(M = Mg, Zn) could make it promising for the application in photovoltaic cells, high power RF applications, as well as power electronic devices.
Collapse
Affiliation(s)
- Md Fahim Al Fattah
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, Canada
| | - Muhammad Ruhul Amin
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada
| | - Mathias Mallmann
- Department of Chemistry, University of Munich (LMU), Butenandtstrasse, Munich, Germany
| | - Safa Kasap
- Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, Canada
| | - Wolfgang Schnick
- Department of Chemistry, University of Munich (LMU), Butenandtstrasse, Munich, Germany
| | - Alexander Moewes
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada
| |
Collapse
|
2
|
Qamar A, Amin MR, Grynko O, Semeniuk O, Reznik A, Moewes A. A Probe of Valence and Conduction Band Electronic Structure of Lead Oxide Films for Photodetectors. Chemphyschem 2019; 20:3328-3335. [PMID: 31612629 DOI: 10.1002/cphc.201900726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 09/15/2019] [Indexed: 11/07/2022]
Abstract
We investigate how the electronic structure of amorphous lead oxide (a-PbO) films deposited on ITO substrate is changed after annealing at various temperatures. Both experimental soft X-ray spectroscopic and density functional theory (DFT) based computational techniques are used to explore the electronic structure of this material. X-ray emission, resonant X-ray inelastic scattering, and X-ray absorption spectroscopic techniques are employed to directly probe the valence and conduction bands. We discover that the films are very stable and remain amorphous when exposed to temperatures below 300 °C. An amorphous-to-polycrystalline (α-PbO phase) transformation occurs during annealing at 400 °C. At 500 °C, an alpha to beta phase change is observed. These structural modifications are accompanied by the band gap value changing from 1.4±0.2 eV to 2.0±0.2 eV upon annealing at 400 °C and to 2.6±0.2 eV upon annealing at 500 °C. A difference between surface and bulk structural properties is found for all samples annealed at 500 °C and above; these samples also exhibit an unexpected suppression of O : 2p density of states (DOS) near the bottom of the conduction band, whereas additional electronic states appear well within the valence band. This study provides a significant step forward to understanding the electronic properties of two polymorphic forms of PbO needed for optimization of this material for use in X-ray sensors.
Collapse
Affiliation(s)
- Amir Qamar
- Department of Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, S7 N5E2, Canada
| | - Muhammad Ruhul Amin
- Department of Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, S7 N5E2, Canada
| | - Oleksandr Grynko
- Chemistry and Materials Science Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B5E1, Canada
| | - Oleksii Semeniuk
- Chemistry and Materials Science Program, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B5E1, Canada.,Advanced Detection Devices Department, Thunder Bay Regional Health Research Institute, 290 Munro Street, Thunder Bay, ON, P7 A7T1, Canada
| | - Alla Reznik
- Advanced Detection Devices Department, Thunder Bay Regional Health Research Institute, 290 Munro Street, Thunder Bay, ON, P7 A7T1, Canada.,Department of Physics, Lakehead University, 955 Oliver Road, Thunder Bay, ON, P7B5E1, Canada
| | - Alexander Moewes
- Department of Physics and Engineering Physics, University of Saskatchewan, 116 Science Place, Saskatoon, SK, S7 N5E2, Canada
| |
Collapse
|
3
|
Jark W. On the advantages of operation in second-order diffraction of blazed gratings in soft X-ray monochromators. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1587-1591. [PMID: 31490148 DOI: 10.1107/s1600577519009421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 07/01/2019] [Indexed: 06/10/2023]
Abstract
The fact that a diffraction grating can provide twofold-smaller bandwidth when operated in second-order diffraction is long known and applied routinely in the laboratory for spectroscopy in the visible and ultraviolet spectral range. A similar routine operation in monochromators for the soft X-ray range is not reported yet. This study will thus address the feasibility of efficient diffraction of soft X-rays in the second order at reflection gratings when operated at grazing angles of incidence. The related systematic study could make profitable use of a recently introduced simple analytical equation for the prediction of the diffraction efficiency of blazed gratings with an ideal sawtooth profile. The predictions are then verified by use of rigorous calculations. The principle finding is that, by operation of gratings with lower groove densities, and thus with higher efficiencies, in higher order diffraction, one can extend the tuning in existing instruments with mechanical/optical limitations to larger photon energies. The performance in terms of transmission and spectral resolving power can be very similar to the performance of a grating with a larger groove density, which would otherwise have to be used for accessing the same energy range. This would allow operation of a single highly efficient grating over a larger photon energy interval at a modern synchrotron radiation source, e.g. from 0.3 to 2.2 keV. Without any requirement for a sophisticated grating exchange scheme, a related instrument promises to be sufficiently stable for the needs imposed by the improvements in source point stability at diffraction-limited storage rings.
Collapse
Affiliation(s)
- Werner Jark
- Elettra - Sincrotrone Trieste SCpA, SS 14 km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| |
Collapse
|
4
|
Jark W. On smart optimization of blazed soft X-ray gratings. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1181-1191. [PMID: 31274442 DOI: 10.1107/s1600577519004120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 03/26/2019] [Indexed: 06/09/2023]
Abstract
The first attempts to calculate the diffraction efficiencies of gratings in the soft X-ray range were made on a scalar model. The results were simple analytical equations, that always severely overestimated the performance of real objects. In this respect, computer programs were found to be more successful, which rigorously consider all diffracted and refracted waves. Consequently soft X-ray gratings are presently optimized using these tools, which requires rather extensive calculations for any instrument optimization as general trends are not immediately obvious. Here it will be shown that the results of the rigorous calculations for gratings with blaze or sawtooth profile can be approximated rather well with a simple analytical equation. This equation contains three multiplicative factors, which deal independently with the effect of the reflectivity, the blaze angle and the groove density. This opens the possibility to initially ignore the effects of the blaze angle and thus to start an optimization in a very general way. Such optimization can be based on isoreflectivity curves and it can then provide `blaze maximum efficiency maps', i.e. simple images. In these latter images, one can identify directly the optimum parameters for a grating, i.e. the groove density providing best efficiency for a requested spectral resolving power. Only successively will the blaze angle have to be fixed. Its choice is then not the result of an extensive optimization process but of a simple calculation applied for the photon energy at which maximum efficiency performance is requested. The maps presented here are used for the optimization of a medium-resolving-power soft X-ray monochromator, which can scan the photon energy range 300-2000 eV.
Collapse
Affiliation(s)
- Werner Jark
- Elettra - Sincrotrone Trieste SCpA, SS 14 km 163.5 in AREA Science Park, Basovizza, 34149 Trieste, Italy
| |
Collapse
|
5
|
X-ray spectroscopic study of amorphous and polycrystalline PbO films, α-PbO, and β-PbO for direct conversion imaging. Sci Rep 2017; 7:13159. [PMID: 29030634 PMCID: PMC5640621 DOI: 10.1038/s41598-017-13703-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 09/25/2017] [Indexed: 11/17/2022] Open
Abstract
We investigated the electronic structure of Lead Oxide (PbO) – one of the most promising photoconductor materials for direct conversion x-ray imaging detectors, using soft x-ray emission and absorption spectroscopy. Two structural configurations of thin PbO layers, namely the polycrystalline and the amorphous phase, were studied, and compared to the properties of powdered α-PbO and β-PbO samples. In addition, we performed calculations within the framework of density functional theory and found an excellent agreement between the calculated and the measured absorption and emission spectra, which indicates high accuracy of our structural models. Our work provides strong evidence that the electronic structure of PbO layers, specifically the width of the band gap and the presence of additional interband and intraband states in both conduction and valence band, depend on the deposition conditions. We tested several model structures using DFT simulations to understand what the origin of these states is. The presence of O vacancies is the most plausible explanation for these additional electronic states. Several other plausible models were ruled out including interstitial O, dislocated O and the presence of significant lattice stress in PbO.
Collapse
|
6
|
Gapontsev VV, Kurmaev EZ, Sathish CI, Yun S, Park JG, Streltsov SV. Spectral and magnetic properties of Na 2RuO 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:405804. [PMID: 28857048 DOI: 10.1088/1361-648x/aa7fd6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present measurements of resistivity, x-ray absorption (XAS) and emission (XES) spectroscopy together with ab initio band structure calculations for quasi two dimensional ruthenate Na2RuO3. Density function calculations (DFT) and XAS and XES spectra both show that Na2RuO3 is a semiconductor with an activation energy of ∼80 meV. Our DFT calculations reveal large magneto-elastic coupling in Na2RuO3 and predict that the ground state of Na2RuO3 should be antiferromagnetic zig-zag.
Collapse
Affiliation(s)
- Vladimir V Gapontsev
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620137, Ekaterinburg, Russia
| | | | | | | | | | | |
Collapse
|
7
|
Ketabi N, de Boer T, Karakaya M, Zhu J, Podila R, Rao AM, Kurmaev EZ, Moewes A. Tuning the electronic structure of graphene through nitrogen doping: experiment and theory. RSC Adv 2016. [DOI: 10.1039/c6ra07546k] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tuning the electronic properties of graphene by doping atoms into its lattice makes it more applicable for electronic devices.
Collapse
Affiliation(s)
- Niloofar Ketabi
- Department of Physics and Engineering Physics
- University of Saskatchewan
- Saskatoon
- Canada
| | - Tristan de Boer
- Department of Physics and Engineering Physics
- University of Saskatchewan
- Saskatoon
- Canada
| | - Mehmet Karakaya
- Department of Physics and Astronomy
- Clemson University
- Clemson
- USA
| | - Jingyi Zhu
- Department of Physics and Astronomy
- Clemson University
- Clemson
- USA
| | - Ramakrishna Podila
- Department of Physics and Astronomy
- Clemson University
- Clemson
- USA
- Clemson Nanomaterials Center
| | - Apparao M. Rao
- Department of Physics and Astronomy
- Clemson University
- Clemson
- USA
- Clemson Nanomaterials Center
| | - Ernst Z. Kurmaev
- X-ray Emission Spectroscopy Lab
- M.N. Mikheev Institute of Metal Physics
- RAS Ural Div
- 620990 Yekaterinburg
- Russia
| | - Alexander Moewes
- Department of Physics and Engineering Physics
- University of Saskatchewan
- Saskatoon
- Canada
| |
Collapse
|
8
|
Chiuzbăian SG, Hague CF, Avila A, Delaunay R, Jaouen N, Sacchi M, Polack F, Thomasset M, Lagarde B, Nicolaou A, Brignolo S, Baumier C, Lüning J, Mariot JM. Design and performance of AERHA, a high acceptance high resolution soft x-ray spectrometer. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:043108. [PMID: 24784594 DOI: 10.1063/1.4871362] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A soft x-ray spectrometer based on the use of an elliptical focusing mirror and a plane varied line spacing grating is described. It achieves both high resolution and high overall efficiency while remaining relatively compact. The instrument is dedicated to resonant inelastic x-ray scattering studies. We set out how this optical arrangement was judged best able to guarantee performance for the 50 - 1000 eV range within achievable fabrication targets. The AERHA (adjustable energy resolution high acceptance) spectrometer operates with an effective angular acceptance between 100 and 250 μsr (energy dependent) and a resolving power well in excess of 5000 according to the Rayleigh criterion. The high angular acceptance is obtained by means of a collecting pre-mirror. Three scattering geometries are available to enable momentum dependent measurements with 135°, 90°, and 50° scattering angles. The instrument operates on the Synchrotron SOLEIL SEXTANTS beamline which serves as a high photon flux 2 × 200 μm(2) focal spot source with full polarization control.
Collapse
Affiliation(s)
- Sorin G Chiuzbăian
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Coryn F Hague
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Antoine Avila
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Renaud Delaunay
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Nicolas Jaouen
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - Maurizio Sacchi
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - François Polack
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - Muriel Thomasset
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - Bruno Lagarde
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - Alessandro Nicolaou
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, B.P. 48, F-91192 Gif-sur-Yvette, France
| | - Stefania Brignolo
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Cédric Baumier
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Jan Lüning
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Jean-Michel Mariot
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| |
Collapse
|