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Zdanowicz E, Herman AP, Opołczyńska K, Gorantla S, Olszewski W, Serafińczuk J, Hommel D, Kudrawiec R. Toward h-BN/GaN Schottky Diodes: Spectroscopic Study on the Electronic Phenomena at the Interface. ACS APPLIED MATERIALS & INTERFACES 2022; 14:6131-6137. [PMID: 35043636 PMCID: PMC8815035 DOI: 10.1021/acsami.1c20352] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/05/2022] [Indexed: 05/27/2023]
Abstract
Hexagonal boron nitride (h-BN), together with other members of the van der Waals crystal family, has been studied for over a decade, both in terms of fundamental and applied research. Up to now, the spectrum of h-BN-based devices has broadened significantly, and systems containing the h-BN/III-V junctions have gained substantial interest as building blocks in, inter alia, light emitters, photodetectors, or transistor structures. Therefore, the understanding of electronic phenomena at the h-BN/III-V interfaces becomes a question of high importance regarding device engineering. In this study, we present the investigation of electronic phenomena at the h-BN/GaN interface by means of contactless electroreflectance (CER) spectroscopy. This nondestructive method enables precise determination of the Fermi level position at the h-BN/GaN interface and the investigation of carrier transport across the interface. CER results showed that h-BN induces an enlargement of the surface barrier height at the GaN surface. Such an effect translates to Fermi level pinning deeper inside the GaN band gap. As an explanation, we propose a mechanism based on electron transfer from GaN surface states to the native acceptor states in h-BN. We reinforced our findings by thorough structural characterization and demonstration of the h-BN/GaN Schottky diode. The surface barriers obtained from CER (0.60 ± 0.09 eV for GaN and 0.91 ± 0.12 eV for h-BN/GaN) and electrical measurements are consistent within the experimental accuracy, proving that CER is an excellent tool for interfacial studies of 2D/III-V hybrids.
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Affiliation(s)
- Ewelina Zdanowicz
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
- Department
of Semiconductor Materials Engineering, Wrocław University of Science and Technology, Wyspiańskiego 27, Wrocław 50-370, Poland
| | - Artur P. Herman
- Department
of Semiconductor Materials Engineering, Wrocław University of Science and Technology, Wyspiańskiego 27, Wrocław 50-370, Poland
| | - Katarzyna Opołczyńska
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
- Institute
of Experimental Physics, University of Wrocław, pl. M. Borna 9, Wrocław 50-204, Poland
| | - Sandeep Gorantla
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Wojciech Olszewski
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Jarosław Serafińczuk
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
- Department
of Nanometrology, Wrocław University
of Science and Technology, Janiszewskiego 11/17, Wrocław 50-372, Poland
| | - Detlef Hommel
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
| | - Robert Kudrawiec
- Łukasiewicz
Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, Wrocław 54-066, Poland
- Department
of Semiconductor Materials Engineering, Wrocław University of Science and Technology, Wyspiańskiego 27, Wrocław 50-370, Poland
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Kopaczek J, Woźniak T, Tamulewicz-Szwajkowska M, Zelewski SJ, Serafińczuk J, Scharoch P, Kudrawiec R. Experimental and Theoretical Studies of the Electronic Band Structure of Bulk and Atomically Thin Mo 1-x W x Se 2 Alloys. ACS OMEGA 2021; 6:19893-19900. [PMID: 34368576 PMCID: PMC8340422 DOI: 10.1021/acsomega.1c02788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
We present studies focused on the evolution of the electronic band structure of the Mo1-x W x Se2 alloy with the tungsten content, which was conducted by combining experimental and theoretical methods. Employed spectroscopic techniques, namely, photoreflectance, photoacoustic spectroscopy, and photoluminescence, allowed observing indirect and direct transitions at high and beyond high-symmetry points of the Brillouin zone (BZ). Two excitons (A and B) associated with the K point of the BZ were observed together with other optical transitions (C and D) related to band nesting. Moreover, we have also identified the indirect transition for the studied crystals. Obtained energies for all transitions were tracked with a tungsten content and compared with results of calculations performed within density functional theory. Furthermore, based on the mentioned comparison, optical transitions were assigned to specific regions of the BZ. Finally, we have obtained bowing parameters for experimentally observed features, for, i.e., thin-film samples: b(A) = 0.13 ± 0.03 eV, b(B) = 0.14 ± 0.03 eV, b(C) = 0.044 ± 0.008 eV, and b(D) = 0.010 ± 0.003 eV.
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Affiliation(s)
- Jan Kopaczek
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wroclaw University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Tomasz Woźniak
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wroclaw University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | | | - Szymon J. Zelewski
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wroclaw University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Jarosław Serafińczuk
- Department
of Nanometrology, Wroclaw University of
Science and Technology, Janiszewskiego 11/17, 50-372 Wroclaw, Poland
| | - Paweł Scharoch
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wroclaw University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Robert Kudrawiec
- Department
of Semiconductor Materials Engineering, Faculty of Fundamental Problems
of Technology, Wroclaw University of Science
and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Zhang B, Wang XJ. Note: A modified optics based technique for suppressing spurious signals in photoreflectance spectra. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:106103. [PMID: 29092464 DOI: 10.1063/1.4993263] [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
A modified optics based technique was developed to effectively suppress spurious background signals encountered in the photoreflectance (PR) spectra obtained from bulk semiconductors and semiconductor microstructures. Based on a traditional PR setup, the novel PR approach utilized an achromatic beam reduction system to narrow the profile of a probe beam, which was subsequently collected by a focus lens coupled with an iris. The new setup guarantees high collection efficiency for probe signals and strong suppression of background signals. Compared with existing PR methods for background minimization, the proposed PR technique is simpler to accomplish, more cost effective, and provides a higher signal-to-noise ratio for the PR spectra.
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Affiliation(s)
- Bin Zhang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
| | - Xing-Jun Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
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Dybała F, Polak MP, Kopaczek J, Scharoch P, Wu K, Tongay S, Kudrawiec R. Pressure coefficients for direct optical transitions in MoS2, MoSe2, WS2, and WSe2 crystals and semiconductor to metal transitions. Sci Rep 2016. [PMID: 27215469 DOI: 10.1063/1.4954157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
The electronic band structure of MoS2, MoSe2, WS2, and WSe2, crystals has been studied at various hydrostatic pressures experimentally by photoreflectance (PR) spectroscopy and theoretically within the density functional theory (DFT). In the PR spectra direct optical transitions (A and B) have been clearly observed and pressure coefficients have been determined for these transitions to be: αA = 2.0 ± 0.1 and αB = 3.6 ± 0.1 meV/kbar for MoS2, αA = 2.3 ± 0.1 and αB = 4.0 ± 0.1 meV/kbar for MoSe2, αA = 2.6 ± 0.1 and αB = 4.1 ± 0.1 meV/kbar for WS2, αA = 3.4 ± 0.1 and αB = 5.0 ± 0.5 meV/kbar for WSe2. It has been found that these coefficients are in an excellent agreement with theoretical predictions. In addition, a comparative study of different computational DFT approaches has been performed and analyzed. For indirect gap the pressure coefficient have been determined theoretically to be -7.9, -5.51, -6.11, and -3.79, meV/kbar for MoS2, MoSe2, WS2, and WSe2, respectively. The negative values of this coefficients imply a narrowing of the fundamental band gap with the increase in hydrostatic pressure and a semiconductor to metal transition for MoS2, MoSe2, WS2, and WSe2, crystals at around 140, 180, 190, and 240 kbar, respectively.
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Affiliation(s)
- F Dybała
- Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - M P Polak
- Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - J Kopaczek
- Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - P Scharoch
- Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - K Wu
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - S Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287, United States
| | - R Kudrawiec
- Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Baranowski M, Kudrawiec R, Latkowska M, Syperek M, Misiewicz J, Sarmiento T, Harris JS. Enhancement of photoluminescence from GaInNAsSb quantum wells upon annealing: improvement of material quality and carrier collection by the quantum well. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:065801. [PMID: 23306016 DOI: 10.1088/0953-8984/25/6/065801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this study we apply time resolved photoluminescence and contactless electroreflectance to study the carrier collection efficiency of a GaInNAsSb/GaAs quantum well (QW). We show that the enhancement of photoluminescence from GaInNAsSb quantum wells annealed at different temperatures originates not only from (i) the improvement of the optical quality of the GaInNAsSb material (i.e., removal of point defects, which are the source of nonradiative recombination) but it is also affected by (ii) the improvement of carrier collection by the QW region. The total PL efficiency is the product of these two factors, for which the optimal annealing temperatures are found to be ~700 °C and ~760 °C, respectively, whereas the optimal annealing temperature for the integrated PL intensity is found to be between the two temperatures and equals ~720 °C. We connect the variation of the carrier collection efficiency with the modification of the band bending conditions in the investigated structure due to the Fermi level shift in the GaInNAsSb layer after annealing.
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Affiliation(s)
- M Baranowski
- Institute of Physics, Wroclaw University of Technology, Wroclaw, Poland.
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