Nanowire Grid Polarization and Polarized Excitonic Emission Observed in Multilayer GaTe

J Phys Chem Lett. 2020 Feb 6;11(3):608-617. doi: 10.1021/acs.jpclett.9b03569. Epub 2020 Jan 9.


In this study, near-infrared (NIR) x-polarized (P-state) light is created from the transmission ray of monoclinic multilayer GaTe near the band edge. The P-state transmittance photons are produced via the transmission light of a ribbonlike multilayer GaTe with a plurality of nanowire grids being parallel and constructed along the y direction (b axis) from 1.56 to 1.62 eV. At 300 K, a P-state excitonic emission at 1.652 eV can be clearly detected in polarized microphotoluminescence (μPL) measurement. The free-exciton extinction energy and recombination lifetime of the band-edge exciton are evaluated and determined to be ΔE = 32 ± 4 meV and τ ≈ 0.032 ns, respectively, for the multilayer GaTe. Polarized microthermoreflectance (μTR) measurement also verifies that the x-polarized transition is allowed while y-polarized (S-state) transition is forbidden in the multilayer GaTe. An asymmetric p-to-p transition along the x polarization is thus inferred to comprise the band edge of multilayer GaTe to form in-plane optical anisotropy.