Anisotropic Quantum Well Electro-Optics in Few-Layer Black Phosphorus

Abstract

The incorporation of electrically tunable materials into photonic structures such as waveguides and metasurfaces enables dynamic, electrical control of light propagation at the nanoscale.Few-layer black phosphorus is a promising material for these applications due to its in-plane anisotropic, quantum well band structure, with a direct band gap that can be tuned from 0.3 eV to 2 eV with number of layers and subbands that manifest as additional optical transitions across a wide range of energies. In this work, we report an experimental investigation of three different, anisotropic electro-optic mechanisms that allow electrical control of the complex refractive index in few-layer black phosphorus from the mid-infrared to the visible: Pauliblocking of intersubband optical transitions (the Burstein-Moss effect); the quantum-confined Stark effect; and the modification of quantum well selection rules by a symmetry-breaking, applied electric field. These effects generate near-unity tuning of the BP oscillator strength for some material thicknesses and photon energies, along a single in-plane crystal axis, transforming absorption from highly anisotropic to nearly isotropic. Lastly, the anisotropy of these electro-optical phenomena results in dynamic control of linear dichroism and

Actively variable-spectrum optoelectronics with black phosphorus

“…b, Angular intensity distribution of the strain-engineered bP-LED calculated with FDTD simulations (FDTD Solutions, Lumerical). c, Table showing the complex refractive indices of the polyimide substrate, bP, and MoS2 from the literature 28,47,[64][65][66] , which was used for the simulation. While the precise computation awaits further study on the refractive index changes of bP with strains (compressive strain and tensile strain), we simply calculated the angular distribution of bP-LED at two different peak wavelengths, using the refractive indices of bP without strain from the literature.…”

Self‐Healable Black Phosphorus Photodetectors

“…In recent years, the emergence of black phosphorus (BP) has provided new ideas for the developments and applications of photoelectronic devices due to its marvelous properties like tunable bandgap with the number of layers (0.3–2.0 eV), high carrier mobility (10 3 cm 2 V −1 s −1 ), high ON/OFF ratios (10 6 ), and in‐plane anisotropy (optical, thermal, and mechanical) characteristics . To date, BP has been widely investigated in a variety of new generation devices with exciting results, including lithium ion batteries, solar cells, field effect transistors (FETs), photothermal therapy, biosensors, and photodetectors (PDs) .…”

Piezoelectricity in Multilayer Black Phosphorus for Piezotronics and Nanogenerators

“…Black phosphorus (BP), which has only recently been investigated as a 2D material, has been a research focus due to its thickness‐dependent bandgap and high carrier mobility . The anisotropic characteristics of BP, including its optical, thermal, mechanical, ionic transport and electronic properties, are oriented according to its anisotropic atomic structure. These characteristics encouraged further investigation leading to the discovery of the piezoelectricity of BP.…”