Semiconductor nanowire (NW) lasers are attractive as integrated on-chip coherent light sources with strong potential for applications in optical communication and sensing. Realizing lasers from individual bulk-type NWs with emission tunable from the near-infrared to the telecommunications spectral region is, however, challenging and requires low-dimensional active gain regions with an adjustable band gap and quantum confinement. Here, we demonstrate lasing from GaAs-(InGaAs/AlGaAs) core-shell NWs with multiple InGaAs quantum wells (QW) and lasing wavelengths tunable from ∼0.8 to ∼1.1 μm. Our investigation emphasizes particularly the critical interplay between QW design, growth kinetics, and the control of InGaAs composition in the active region needed for effective tuning of the lasing wavelength. A low shell growth temperature and GaAs interlayers at the QW/barrier interfaces enable In molar fractions up to ∼25% without plastic strain relaxation or alloy intermixing in the QWs. Correlated scanning transmission electron microscopy, atom probe tomography, and confocal PL spectroscopy analyses illustrate the high sensitivity of the optically pumped lasing characteristics on microscopic properties, providing useful guidelines for other III-V-based NW laser systems.
Semiconductor nanowire (NW) lasers are nanoscale coherent light sources that exhibit a small footprint, lowthreshold lasing characteristics, and properties suitable for monolithic and site-selective integration onto Si photonic circuits. An important milestone on the way toward novel onchip photonic functionalities, such as injection locking of laser emission and all-optical switching mediated by coherent optical coupling and feedback, is the integration of individual, deterministically addressable NW lasers on Si waveguides with efficient coupling and mode propagation in the underlying photonic circuit. Here, we demonstrate the monolithic integration of single GaAs-based NW lasers directly onto lithographically defined Si ridge waveguides (WG) with low threshold power densities of 19.8 μJ/cm 2 when optically excited. The lasing mode of individual NW lasers is shown to couple efficiently into propagating modes of the underlying orthogonal Si WG, preserving the lasing characteristics during mode propagation in the WG in good agreement with Finite-Difference Time-Domain (FDTD) simulations. Using a WG structure with a series of mask openings along the central mode propagation axis, we further illustrate the out-coupling properties of both spontaneous and stimulated emission and demonstrate propagation of the lasing mode over distances >60 μm, despite absorption in the silicon dominating the propagation losses.
Nanowires (NWs) hold great potential in advanced thermoelectrics due to their reduced dimensions and low‐dimensional electronic character. However, unfavorable links between electrical and thermal conductivity in state‐of‐the‐art unpassivated NWs have, so far, prevented the full exploitation of their distinct advantages. A promising model system for a surface‐passivated one‐dimensional (1D)‐quantum confined NW thermoelectric is developed that enables simultaneously the observation of enhanced thermopower via quantum oscillations in the thermoelectric transport and a strong reduction in thermal conductivity induced by the core–shell heterostructure. High‐mobility modulation‐doped GaAs/AlGaAs core–shell NWs with thin (sub‐40 nm) GaAs NW core channel are employed, where the electrical and thermoelectric transport is characterized on the same exact 1D‐channel. 1D‐sub‐band transport at low temperature is verified by a discrete stepwise increase in the conductance, which coincided with strong oscillations in the corresponding Seebeck voltage that decay with increasing sub‐band number. Peak Seebeck coefficients as high as ≈65–85 µV K−1 are observed for the lowest sub‐bands, resulting in equivalent thermopower of S2σ ≈ 60 µW m−1 K−2 and S2G ≈ 0.06 pW K−2 within a single sub‐band. Remarkably, these core–shell NW heterostructures also exhibit thermal conductivities as low as ≈3 W m−1 K−1, about one order of magnitude lower than state‐of‐the‐art unpassivated GaAs NWs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.