Ultrafast direct modulation of a single-mode photonic crystal nanocavity light-emitting diode

Shambat, Gary; Ellis, Bryan; Majumdar, Arka; Petykiewicz, Jan; Mayer, Marie A.; Sarmiento, Tomás; Harris, James S.; Häller, E. E.; Vučković, Jelena

doi:10.1038/ncomms1543

Cited by 122 publications

(79 citation statements)

References 25 publications

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“…This is important for future integration of these defects with electrically stimulated devices and photonic resonators. [ 47 ] Figure 7 a shows the excited state lifetimes of the fl uorescent defects excited by sub-bandgap 405 nm excitation. The as-received nanoparticles and Zn annealed nanoparticles exhibit a similar short lifetime of τ = 10 ± 0.3 ns and τ = 13 ± 0.4 ns for the 1.75 and 2.32 eV emission respectively.…”

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confidence: 99%

Photophysics of Point Defects in ZnO Nanoparticles

Choi

Phillips

Aharonovich

et al. 2015

Advanced Optical Materials

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including oxygen vacancies ( V O ), [ 6 ] and zinc vacancies ( V Zn ), [ 7 ] interstitials (Zn i , O i ), [ 8 ] and antisite defects (Zn O , O Zn ) [ 9 ] as well as chemical impurities such as Cu. [ 10 ] The need to characterize point defects in ZnO is further amplifi ed with the recent applications of ZnO nanoparticles as hosts of single emitters for quantum information processing [11][12][13] and their use in random lasing [ 14 ] and other advanced sensing technologies. [ 15 ] These applications require precise control over the defect engineering in ZnO nanoparticles. Consequently, correlative characterization of point defects will be valuable to explore the luminescence properties and affi liate them with their chemical and paramagnetic spin features.In this work we perform comprehensive studies on the formation and photophysical properties of point defects in ZnO nanoparticles. In particular, we employ correlative characterization techniques to assign the optical emission peaks and electron paramagnetic resonance (EPR) lines to specifi c defects in ZnO nanoparticles. Our results provide new insight into optical luminescence properties of ZnO nanoparticles and promote them as potential candidate for nanophotonic technologies. [ 16 ] Results and DiscussionAfter being annealed in an Ar or Zn vapor environment at 700-900 °C the as-received ZnO nanoparticles (diameter ≈ 20 nm) coalescence [ 17,18 ] and display faceted morphologies ( Figure 1 ). The nanoparticles increase in average size up to about 120 nm after annealing in inert gas (Ar) or oxygen, and up to 150 nm for annealing in Zn vapor at 900 °C [see Figures S1 and S2, Supporting Information for nanoparticle sizes obtained from scanning electron microscopy (SEM) image and X-ray diffraction (XRD) analysis]. Since the Bohr radius of ZnO is 2.34 nm, [ 19 ] the nanoparticles are large enough to avoid quantum size effects but still possess a suffi ciently large surface area to allow defect engineering.To investigate the occurrence of defects in ZnO nanoparticles, EPR spectroscopy was performed. Figure 2 a shows EPR spectra of the as-received, O 2 annealed, Zn vapor annealed ZnO nanoparticles and a bare Si(100) substrate for comparison. The as-received ZnO nanoparticles exhibit a strong signal at g = 1.96, which has been previously assigned to zinc vacancies (V Zn − ), [ 20 ] oxygen interstitials (O i − ), [ 20 ] zinc interstitials (Zn i + ) [ 21 ] and to electrons in weakly bound or conduction band (CB) Zinc oxide (ZnO) nanoparticles have recently been identifi ed as a promising candidate for advanced nanophotonics applications and quantum technologies. This work reports the formation of luminescent point defects and describes their photophysical properties. In particular, it is shown using correlative photoluminescence, cathodoluminescence, electron paramagnetic resonance (EPR), and X-ray absorption near-edge spectroscopy that green luminescence at 2.48 eV and an EPR line at g = 2.00 belong to a surface oxygen vacancy (V o,s + ) center, while a second green emi...

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confidence: 99%

Photophysics of Point Defects in ZnO Nanoparticles

Choi

Phillips

Aharonovich

et al. 2015

Advanced Optical Materials

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Abstract: Light-emitting diodes are of importance for lighting, displays, optical interconnects, logic and sensors [1][2][3][4][5][6][7][8] . Hence the development of new systems that allow improvements in their efficiency, spectral properties, compactness and integrability could have significant ramifications.

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confidence: 99%

Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p–n junctions

et al. 2014

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Light-emitting diodes are of importance for lighting, displays, optical interconnects, logic and sensors [1][2][3][4][5][6][7][8] . Hence the development of new systems that allow improvements in their efficiency, spectral properties, compactness and integrability could have significant ramifications. Monolayer transition metal dichalcogenides have recently emerged as interesting candidates for optoelectronic applications due to their unique optical properties [9][10][11][12][13][14][15][16] . Electroluminescence has already been observed from monolayer MoS2 devices 17,18 . However, the electroluminescence efficiency was low and the linewidth broad due both to the poor optical quality of MoS2 and to ineffective contacts. Here, we report electroluminescence from lateral p-n junctions in monolayer WSe2 induced electrostatically using a thin boron nitride support as a dielectric layer with multiple metal gates beneath.This structure allows effective injection of electrons and holes, and combined with the high optical quality of WSe2 it yields bright electroluminescence with 1000 times smaller injection current and 10 times smaller linewidth than in MoS2 17,18 . Furthermore, by increasing the injection bias we can tune the electroluminescence between regimes of impurity-bound, charged, and neutral excitons. This system has the required ingredients for new kinds of optoelectronic devices such as spin-and valley-polarized light-emitting diodes, on-chip lasers, and two-dimensional electro-optic modulators. Main TextFew-layer group-VIB transition metal dichalcogenides (TMDs) represent a class of semiconductors in the two-dimensional (2D) limit 9,10,19 . Due to their large carrier effective mass and the reduced screening in 2D, electron-hole interactions are much stronger than in conventional semiconductors. This leads to large binding energies for both charged and neutral excitons which as a result are spectrally sharp, robust, and amenable to electrical manipulation 16,20,21 . In addition, the large spin-orbit coupling 22 and the acentric structure of TMDs provides a connection between spin and valley degrees of freedom 14 , light polarization 11,13,15,16 , and magnetic and electric fields 23 that can be exploited for new kinds of device operation.Although in bulk TMDs the band gap is indirect, in the limit of a single monolayer it becomes direct 9,10 , fulfilling the most basic requirement for efficient light emission. Indeed, electroluminescence (EL) has already been reported from monolayer MoS2 field-effect transistors (FETs), occurring near the Schottky contact with a metal 17 or with highly doped silicon 18 .However, the efficiency and spectral quality was much lower than has been demonstrated for other nanoscale light emitters such as carbon nanotubes 7 , for two reasons. First, efficient EL requires effective injection of both electrons and holes into the active region, which should therefore be within a p-n junction. Second, MoS2 is known to have poorer optical quality than other group VIB TMDs, possi...

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“…F ree-standing nano-membranes have been fabricated from various materials, such as Si-based inorganics [1][2][3][4][5][6] , thin metal foils 7,8 and other types of nano-materials [9][10][11][12][13][14] , for use in a wide range of applications including shadow masking 3,4 , molecular separation 5,6,15 , plasmonics 4,7 , energy devices [16][17][18] and bio-inspired microfluidic devices 19,20 . In general, a series of standard semiconductor processes and/or specific materials 7,21 with high mechanical rigidity have been required to maintain the membrane's shape firmly without mechanical fracture or tear against external forces that arise during the handling process.…”

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confidence: 99%

Replication of flexible polymer membranes with geometry-controllable nano-apertures via a hierarchical mould-based dewetting

et al. 2014

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Membranes with nano-apertures are versatile templates that possess a wide range of electronic, optical and biomedical applications. However, such membranes have been limited to silicon-based inorganic materials to utilize standard semiconductor processes. Here we report a new type of flexible and free-standing polymeric membrane with nano-apertures by exploiting high-wettability difference and geometrical reinforcement via multiscale, multilevel architecture. In the method, polymeric membranes with various pore sizes (50-800 nm) and shapes (dots, lines) are fabricated by a hierarchical mould-based dewetting of ultravioletcurable resins. In particular, the nano-pores are monolithically integrated on a two-level hierarchical supporting layer, allowing for the rapid (o5 min) and robust formation of multiscale and multilevel nano-apertures over large areas (2 Â 2 cm 2 ).

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Ultrafast direct modulation of a single-mode photonic crystal nanocavity light-emitting diode

Cited by 122 publications

References 25 publications

Photophysics of Point Defects in ZnO Nanoparticles

Photophysics of Point Defects in ZnO Nanoparticles

Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p–n junctions

Replication of flexible polymer membranes with geometry-controllable nano-apertures via a hierarchical mould-based dewetting

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