Topological insulator with negative spin-orbit coupling and transition between Weyl and Dirac semimetals in InGaN-based quantum wells

Łepkowski, S. P.; Bardyszewski, W.

doi:10.1038/s41598-018-33461-4

Cited by 12 publications

(52 citation statements)

References 41 publications

(86 reference statements)

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“…[132][133][134] In future perspectives, one can expect that InGaN pseudo-substrates will make it possible to reach the terahertz emission from InN/InGaN QWs and close the energy gap in these heterostructures, leading to the topological phase transition. [135] The theoretically proposed possibility of achieving the topological insulator state in InN-based QWs is currently of significant scientific interest due to their potential applications in piezotronics, spintronics, and topological electronics (topotronics). [136][137][138][139][140][141][142]…”

Section: Color Conversion Technology For Rgb Displaymentioning

confidence: 99%

Recent Progress in Micro‐LED‐Based Display Technologies

Sajjad

Johar

Hernández-Gutiérrez

et al. 2022

Laser & Photonics Reviews

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147

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The demand for high-performance displays is continuously increasing because of their wide range of applications in smart devices (smartphones/watches), augmented reality, virtual reality, and naked eye 3D projection. High-resolution, transparent, and flexible displays are the main types of display to be used in future. In the above scenario, the micro-LEDs (light-emitting diodes) display which has outstanding features, such as low power consumption, wider color gamut, longer lifetime, and short response-time, can replace traditional liquid crystal displays and organic LEDs-based display technologies. However, to attain a remarkable position in future display technology, the micro-LEDs need to overcome problems associated with mass transfer and its high cost of manufacturing. Besides micro-LEDs, the other option for future displays includes the usage of color conversion medium (phosphor/ quantum dots) to convert some of the blue light into other colors. In this review, the various mass transfer display technologies and color conversion strategies which are being used for the realization of a full-color display are discussed.

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Section: Color Conversion Technology For Rgb Displaymentioning

confidence: 99%

Recent Progress in Micro‐LED‐Based Display Technologies

Sajjad

Johar

Hernández-Gutiérrez

et al. 2022

Laser & Photonics Reviews

Self Cite

147

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“…The huge built-in electric field also induces the Rashba SOI, which significantly influences the bulk energy gap in the TI phase,

. Although GaN and InN are technologically important semiconductors, the issue of the SOI in these materials is still under scientific debate [ 13 ]. In InN/GaN topological QWs, the

can reach 5 meV when the positive SOI of the order of a few milli-electron volts is assumed in GaN and InN crystals, or it can be about 1.25 meV when the negative SOI in InN is considered [ 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

“…Although GaN and InN are technologically important semiconductors, the issue of the SOI in these materials is still under scientific debate [ 13 ]. In InN/GaN topological QWs, the

are significantly smaller than that for HgTe/CdTe and InAs/GaSb/AlSb QWs [ 14 , 15 , 16 ], they are large enough to allow for the experimental verification of the QSHE in these structures [ 17 , 18 ].…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, the problem is that to achieve the TPT in InN/GaN QWs, the QW width should be at least four monolayers ( MLs ) and the growth of such thick and fully strained structures is extremely difficult, due to large strain reaching 11%. This problem can be partially overcome by applying InGaN alloys [ 13 , 19 , 20 ]. However, in In x Ga 1−x N/GaN QWs, the critical thickness for obtaining the TI state increases faster with decreasing In content in the QWs than the critical thickness for pseudomorphic growth [ 13 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

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Polarization-Induced Phase Transitions in Ultra-Thin InGaN-Based Double Quantum Wells

Łepkowski

Anwar

2022

Nanomaterials

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We investigate the phase transitions and the properties of the topological insulator in InGaN/GaN and InN/InGaN double quantum wells grown along the [0001] direction. We apply a realistic model based on the nonlinear theory of elasticity and piezoelectricity and the eight-band k·p method with relativistic and nonrelativistic linear-wave-vector terms. In this approach, the effective spin‒orbit interaction in InN is negative, which represents the worst-case scenario for obtaining the topological insulator in InGaN-based structures. Despite this rigorous assumption, we demonstrate that the topological insulator can occur in InGaN/GaN and InN/InGaN double quantum wells when the widths of individual quantum wells are two and three monolayers (MLs), and three and three MLs. In these structures, when the interwell barrier is sufficiently thin, we can observe the topological phase transition from the normal insulator to the topological insulator via the Weyl semimetal, and the nontopological phase transition from the topological insulator to the nonlocal topological semimetal. We find that in InGaN/GaN double quantum wells, the bulk energy gap in the topological insulator phase is much smaller for the structures with both quantum well widths of 3 MLs than in the case when the quantum well widths are two and three MLs, whereas in InN/InGaN double quantum wells, the opposite is true. In InN/InGaN structures with both quantum wells being three MLs and a two ML interwell barrier, the bulk energy gap for the topological insulator can reach about . We also show that the topological insulator phase rapidly deteriorates with increasing width of the interwell barrier due to a decrease in the bulk energy gap and reduction in the window of In content between the normal insulator and the nonlocal topological semimetal. For InN/InGaN double quantum wells with the width of the interwell barrier above five or six MLs, the topological insulator phase does not appear. In these structures, we find two novel phase transitions, namely the nontopological phase transition from the normal insulator to the nonlocal normal semimetal and the topological phase transition from the nonlocal normal semimetal to the nonlocal topological semimetal via the buried Weyl semimetal. These results can guide future investigations towards achieving a topological insulator in InGaN-based nanostructures.

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“…In addition to providing bandgap tunability, MQW SLs allow for strain transfer to the barriers, and may reduce the compositional fluctuations and indium clustering that significantly affect the bandgap 12 , 13 . Moreover, a theoretically proposed and experimentally indicated possibility to achieve topological insulator behavior using In x Ga 1− x N/GaN SLs with high indium content could revolutionize III-nitride applications by opening up new fields in spintronics and quantum computing 14 – 16 .…”

Section: Introductionmentioning

confidence: 99%

Substitutional synthesis of sub-nanometer InGaN/GaN quantum wells with high indium content

Vasileiadis

Lymperakis

Adikimenakis

et al. 2021

Sci Rep

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InGaN/GaN quantum wells (QWs) with sub-nanometer thickness can be employed in short-period superlattices for bandgap engineering of efficient optoelectronic devices, as well as for exploiting topological insulator behavior in III-nitride semiconductors. However, it had been argued that the highest indium content in such ultra-thin QWs is kinetically limited to a maximum of 33%, narrowing down the potential range of applications. Here, it is demonstrated that quasi two-dimensional (quasi-2D) QWs with thickness of one atomic monolayer can be deposited with indium contents far exceeding this limit, under certain growth conditions. Multi-QW heterostructures were grown by plasma-assisted molecular beam epitaxy, and their composition and strain were determined with monolayer-scale spatial resolution using quantitative scanning transmission electron microscopy in combination with atomistic calculations. Key findings such as the self-limited QW thickness and the non-monotonic dependence of the QW composition on the growth temperature under metal-rich growth conditions suggest the existence of a substitutional synthesis mechanism, involving the exchange between indium and gallium atoms at surface sites. The highest indium content in this work approached 50%, in agreement with photoluminescence measurements, surpassing by far the previously regarded compositional limit. The proposed synthesis mechanism can guide growth efforts towards binary InN/GaN quasi-2D QWs.

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Topological insulator with negative spin-orbit coupling and transition between Weyl and Dirac semimetals in InGaN-based quantum wells

Cited by 12 publications

References 41 publications

Recent Progress in Micro‐LED‐Based Display Technologies

Recent Progress in Micro‐LED‐Based Display Technologies

Polarization-Induced Phase Transitions in Ultra-Thin InGaN-Based Double Quantum Wells

Substitutional synthesis of sub-nanometer InGaN/GaN quantum wells with high indium content

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