Observation of Photoluminescence from a Natural van der Waals Heterostructure

Abstract

Van der Waals heterostructures comprised of two-dimensional (2D) materials offer a platform to obtain materials by design with unique electronic properties. Franckeite (Fr) is a naturally occurring van der Waals heterostructure comprised of two distinct alternately stacked semiconducting layers; (i) SnS${}_2$ layer and (ii) Pb${}_3$SbS${}_4$. Though both layers in the heterostructure are semiconductors, the photoluminescence from Franckeite remains elusive. Here, we report the observation of photoluminescence (PL) from Franckeite for the first time. We observed two PL peaks at ~ 1.93 eV and ~ 2.11 eV. By varying the temperature from 1.5 K to 80 K, we found that the PL peak position redshifts and the integrated intensity decreases slowly as we increase the temperature. We observed linear dependence of photoluminescence integrated intensity on excitation laser power indicating that the photoluminescence is originating from free excitons in the SnS${}_2$ layer of Fr. By comparing the PL from Fr with the PL from a monolayer MoS${}_2$, we determined that the PL quantum efficiency from Fr is an order of magnitude lower than that of a monolayer MoS${}_2$. Our study provides a fundamental understanding of the optical behavior in a complex naturally occurring van der Waals heterostructure, and may pave an avenue toward developing nanoscale optical and optoelectronic devices with tailored properties.

8 pages, 5 Figures, Accepted to Applied Physics Letter

References in corpus (8)

• 2D materials and van der Waals heterostructures
• Boron nitride substrates for high-quality graphene electronics
• Recent progress in the assembly of nanodevices and van der Waals heterostructures by deterministic placement of 2D materials
• Moiré excitons: from programmable quantum emitter arrays to spin-orbit coupled artificial lattices
• Probing excitonic states in ultraclean suspended two-dimensional semiconductors by photocurrent spectroscopy
• Phase segregation facilitates exfoliation of franckeite crystals to a single unit cell thickness
• Franckeite: a naturally occurring van der Waals heterostructure
• Photoresponse of Natural van der Waals Heterostructures

Cited by in corpus (1)

• Investigation of the Nonlinear Optical Frequency Conversion in Ultrathin Franckeite Heterostructures