Strain tuning of the emission axis of quantum emitters in an atomically thin semiconductor

Abstract

Strain engineering is a natural route to control the electronic and optical properties of two-dimensional (2D) materials. Recently, 2D semiconductors have also been demonstrated as an intriguing host of strain-induced quantum-confined emitters with unique valley properties inherited from the host semiconductor. Here, we study the continuous and reversible tuning of the light emitted by such localized emitters in a monolayer tungsten diselenide embedded in a van der Waals heterostructure. Biaxial strain is applied on the emitters via strain transfer from a lead magnesium niobate–lead titanate (PMN-PT) piezoelectric substrate. Efficient modulation of the emission energy of several localized emitters up to 10 meV has been demonstrated on application of a voltage on the piezoelectric substrate. Further, we also find that the emission axis rotates by ∼ 40 ∘ as the magnitude of the biaxial strain is varied on these emitters. These results elevate the prospect of using all electrically controlled devices where the property of the localized emitters in a 2D host can be engineered with elastic fields for an integrated opto-electronics and nano-photonics platform.

Strain-Correlated Localized Exciton Energy in Atomically Thin Semiconductors

“…It has been shown that nanopillars with equal diameter are associated with a random number of emitters per site and that these emitters can have widely distributed emission energies over 100 meV, even for very small structures of 100 nm size. 16,20 Tuning of emission energy has been demonstrated through applying an out-of-plane electric field 27 or in-plane strain, 28,29 but the tuning range of 2−20 meV is much smaller than the inhomogeneous distribution of the emission energy. Also, the local in-plane strain applied to WSe 2 structures has only been simulated rather than experimentally measured.…”

“…Also, the local in-plane strain applied to WSe 2 structures has only been simulated rather than experimentally measured. 28,29 On the other hand, there have been experimental and theoretical efforts to attribute emitter creation in these systems to the intrinsic defect-state 30 or the combination of strain and intrinsic defects. 31 In this work, we elucidate the role of strain by a careful study of the emission energy of bright localized emitters hosted by atomically thin WSe 2 , along with its relationship to the local strain induced by mirco-structures.…”

“…It has been shown that nanopillars with equal diameter are associated with a random number of emitters per site and that these emitters can have widely distributed emission energies over 100 meV, even for very small structures of 100 nm size. , Tuning of emission energy has been demonstrated through applying an out-of-plane electric field or in-plane strain, , but the tuning range of 2–20 meV is much smaller than the inhomogeneous distribution of the emission energy. Also, the local in-plane strain applied to WSe 2 structures has only been simulated rather than experimentally measured. , On the other hand, there have been experimental and theoretical efforts to attribute emitter creation in these systems to the intrinsic defect-state or the combination of strain and intrinsic defects . In this work, we elucidate the role of strain by a careful study of the emission energy of bright localized emitters hosted by atomically thin WSe 2 , along with its relationship to the local strain induced by mirco-structures.…”

Radiative control of localized excitons at room temperature with an ultracompact tip-enhanced plasmonic nano-cavity

“…Furthermore, a nanocube cavity array was exploited to induce strain and drive more efficient X L emission through Purcell enhancement [14], yet without the ability to control their radiative emission properties. As further practical applications, experiments inducing X L with nano-structures and controlling its frequency through actuators were reported [15,16]. However, these studies have only been performed at cryogenic temperatures because of the small exciton binding energy of X L [17], which leads to a much lower quantum yield at room temperature compared to the overwhelming radiative emission of neutral exciton (X 0 ) [18,19].…”

Dynamic modulation of phonon-assisted transitions in quantum defects in monolayer transition-metal dichalcogenide semiconductors

“…8 These systems have, so far, demonstrated promising properties including quantum emission up to room temperature, 8,17,18 electrostatic control of spin-valley-photon interfaces in TMDCs, [19][20][21] and coherence times up to microseconds. 22,23 The possibility of deterministic positioning 24,25 and control 26 of optically active emitters via strain engineering has also been demonstrated. Importantly, 2D material platforms also offer the opportunity to image 27 and controllably fabricate quantum defects at atomically precise locations using present day scanning probe technologies like aberration corrected transmission electron microscopy and low tem-perature scanning tunnelling microscopy.…”