Optically tunable charge carrier injection in monolayer MoS 2
- PDF / 1,288,626 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 35 Downloads / 238 Views
Optically tunable charge carrier injection in monolayer MoS2 Geeta Sharma1 · Shraddha M. Rao1 · Bhanu Pratap Singh1 · Parinda Vasa1 Received: 8 May 2020 / Accepted: 22 July 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract We report on excitation laser power-dependent Raman and photoluminescence (PL) measurements on gold nanoparticles– monolayer MoS2 hybrid nanostructures. Excitation of localized surface plasmon resonances in gold nanoparticles and their subsequent non-radiative relaxation inject charge carriers (electrons) into the adjacent monolayer M oS2. Due to the noncentrosymmetric nature of monolayer MoS2, the localized electron doping induces lattice compression via inverse piezoelec1 tric response. The resultant lattice distortion manifests as a shift as well as broadening of A1g (Γ) and E2g (Γ) MoS2 Raman 1 modes. A splitting of E2g (Γ) mode is also observed. The PL spectra reveal power-dependent enhancement of trion feature, which again is a signature of an increasing electron doping. The observed effects are confirmed to be doping related as they are absent in monolayer M oS2 without gold nanoparticles. Our observations reveal that charge carrier injection is effectively controlled by varying the excitation laser power, which may aid in optically tuning physical response of MoS2 hybrid nanostructures and devices. Keywords 2D semiconductors · Gold nanoparticles · Surface plasmon resonance · Raman spectroscopy · Charge carrier injection
1 Introduction In recent times, 2-dimensional (2D) transition metal dichalcogenide (TMDC) semiconductors comprising van der Waals bonded atomic layers have received much attention as they are promising candidates for exploring 2D physics as well as developing modern-day electronic and optoelectronic devices [1–3]. TMDCs exhibit intriguing properties arising from an unique combination of large spin–orbit coupling of the constituent atoms, crystal structure, and an enhanced Coulomb interaction due to the quantum confinement [2, 3]. Among them, monolayer M oS2 having direct bandgap of ∼ 2 eV is a widely used prototypical system for investigating fundamental physics and has found wide-ranging applications due to its favourable optical, mechanical and transport characteristics [3–9]. Another interesting feature of monolayer M oS2 is that its physical properties can be effectively tailored through stacking, strain engineering and carrier doping [9–13]. * Parinda Vasa [email protected] 1
Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076, India
An interesting possibility of achieving such a tunability optically is by making hybrid systems with metal nanostructures supporting surface plasmon resonances (SPRs). Plasmonic nanostructures can confine light to length scales much shorter than excitation photon wavelengths, significantly enhancing the local electric field in the vicinity of metal nanostructures [14–16]. Interaction of these near-fields with 2D semiconductor can strongly influence its material as wel
Data Loading...
