Dirac point induced ultralow-threshold laser and giant optoelectronic quantum oscillations in graphene-based heterojunctions

Haider, Golam; Ravindranath, Rini; Chen, Tzu-Pei; Roy, Prathik; Roy, P.; Cai, Shu-Yi; Chen, Yang‐Fang

doi:10.1038/s41467-017-00345-6

Cited by 28 publications

(19 citation statements)

References 56 publications

(65 reference statements)

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“…Graphene quantum dots (GQDs), composed of a single- or few-layered graphite cores connecting with peripheral functional groups, − have attracted great attention and been extensively developed because of their distinctive electronic and optical characteristics − and potential applications in optoelectronics. − One of the most important characteristics of GQDs is their transformation from zero- to nonzero-bandgap semiconductors when the graphene size is reduced to nanometer scale, making them possible for one of the smallest optical gain materials for lasing. As compared to traditional semiconductor quantum dots (QDs), , other important properties such as good solubility in solvents, nontoxicity, and simple synthesis process have made GQDs a promising alternative for solution-processed laser sources with low fabrication cost yet high device performance.…”

mentioning

confidence: 99%

Graphene Quantum Dot Vertical Cavity Surface-Emitting Lasers

et al. 2019

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Nonzero-bandgap graphene quantum dots (GQDs) are novel optical gain materials promising for solution-processed light sources with high cost efficiency and device performance. Currently, there have only been a few reports on the realization of GQDs-based lasers. Herein, we demonstrate for the first time roomtemperature lasing emission with green gamut from GQDs in a vertical optical cavity composed of Ta 2 O 5 /SiO 2 dielectric distributed Bragg reflectors (DBRs). The lasing is enabled by the unique design of the DBR, which not only provides a wide stopband spectrally overlapping with the emission of the GQDs but also allows high transmittance of optical excitation in the UV-light region. This demonstration is a clear evidence of the use of GQDs as optical gain materials and represents an important step forward toward their potential applications in wide-gamut laser displays and projectors.

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confidence: 99%

Graphene Quantum Dot Vertical Cavity Surface-Emitting Lasers

et al. 2019

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“…[38][39][40]63,67,68] As the emitted photon intensity is inversely proportional to the radiative recombination rate, the observed shortening of lifetime fits well with the underlying emission mechanism. [69,70] This fast decay component is absent at higher temperatures in the measured dynamics (see Figure 6B and Figure S13B (Supporting Information)) because lattice phonons destroy the coherence between excitons. Moreover, the spectrally overlap of the emission from different emissive channels remains unresolved by differential reflectivity measurement.…”

Section: Interlayer Coupling Induced Change Of Exciton Decay Dynamicsmentioning

confidence: 95%

Superradiant Emission from Coherent Excitons in van Der Waals Heterostructures

Haider

Sampathkumar

Verhagen

et al. 2021

Adv Funct Materials

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Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantumemitting devices with unmatched design freedom and spectral tunability.

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“…Thus, h-SLG tend to show slightly stronger GERS signals compared with p-SLG (Figures 3b and 4b). [13,16,18,51,52]…”

Section: Gers-based Sensing Of Methylene Blue On P-slg and H-slgmentioning

confidence: 99%

“…At ≈0 V applied bias, the near resonance energy to the HOMO level of the MB cause efficient energy transfer resulting strong Raman signal. [13,16,18,51,52] The position of the Fermi energy of h-SLG at ≈0 V and the HOMO-LUMO energy of MB is schematically shown in Figure 6d. However, the overall Raman intensity starts reducing after 0 V. It continues in a reduced-intensity state during the reverse cycle, which is attributed to the continuous exposure of the sample to the laser, causing mild degradation.…”

Section: Ge-specs For Sensing Of Mb On P-slg and H-slgmentioning

confidence: 99%

Toward Graphene‐Enhanced Spectroelectrochemical Sensors

Kaushik

Sonia

Haider

et al. 2022

Adv Materials Inter

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The SERS effect arises mainly from electromagnetic (EM) and chemical (CM) enhancement of the Raman signal. [3] The EM enhancement is on the order of ≈|E| 4 , amplifying signals >10 8 , where E is the intensity of the EM field. On the other hand, CM enhancement has been shown to enhance the signal ≈10-100×. Nevertheless, SERS enhancement is contingent on the quality of the substrate. Preparation of a suitable substrate requires rigorous micro/nanofabrication processes, such as electrochemical or high vacuum deposition of noble metals (e.g., Ag, Au, Cu) or the selfassembly of size-controlled colloidal noble metal nanoparticles, which are very complex, contaminated, and not homogenous, leading to a lowered SERS effect. Moreover, when metal-based rough substrates, such as Ag or Cu, are used for SERS, they tend to oxidize, which prevents their use in some applications. Additionally, noble metals have relatively poor biological compatibility, hindering their use in biomedical applications.Recently, graphene-enhanced Raman spectroscopy (GERS) has emerged as a novel technique where graphene-based ultra-smooth substrates exhibit strong Raman enhancement from adsorbed molecules. [4][5][6] Graphene is cheap, easy to produce, and remains stable even in relatively harsh conditions. The flat and chemically inert surface and environmentally friendly nature of graphene make it compatible for widespread use including biosensing, biomedical, and environmental applications. [7][8][9] The GERS technique is associated with the CM enhancement mechanism, where the charge transfer occurs between adsorbed molecules and the substrate. [4,10] As the surface plasmon on graphene is in the terahertz range rather than the visible range, graphene does not support EM enhancement by the excitation of visible energy photons. [11] Chemical mechanism-initiated GERS facilitates molecular selectivity, enhancing the charge transfer between the molecules and the graphene. The high stability and reproducibility of the Raman enhanced spectra from graphene makes GERS more suitable for applications than SERS. [12] It has been previously reported that the enhancement from GERS on nitrogen-doped graphene was about ten times higher than SERS with the same probe molecules, while for pristine graphene, it was five times higher. [13] Different molecules have been probed with GERS, making it an effective approach for sensing. [14,15] Theoretical and experimental studies have been conducted to obtain more insight into the mechanism

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Dirac point induced ultralow-threshold laser and giant optoelectronic quantum oscillations in graphene-based heterojunctions

Cited by 28 publications

References 56 publications

Graphene Quantum Dot Vertical Cavity Surface-Emitting Lasers

Graphene Quantum Dot Vertical Cavity Surface-Emitting Lasers

Superradiant Emission from Coherent Excitons in van Der Waals Heterostructures

Toward Graphene‐Enhanced Spectroelectrochemical Sensors

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