Plasmonic antenna coupling to hyperbolic phonon-polaritons for sensitive and fast mid-infrared photodetection with graphene

Sebastián Castilla,Seyoon Kim,Tetiana Slipchenko,Khannan Rajendran,Klaas-Jan Tielrooij,Takashi Taniguchi,Luis Martín-Moreno,Jordan Goldstein,Frank H L Koppens,Rainer Hillenbrand,Elefterios Lidorikis,Kenji Watanabe,Marta Autore,Dirk Englund,Varun-Varma Pusapati,Ioannis Vangelidis

doi:10.1038/s41467-020-18544-z

Abstract

Integrating and manipulating the nano-optoelectronic properties of Van der Waals heterostructures can enable unprecedented platforms for photodetection and sensing. The main challenge of infrared photodetectors is to funnel the light into a small nanoscale active area and efficiently convert it into an electrical signal. Here, we overcome all of those challenges in one device, by efficient coupling of a plasmonic antenna to hyperbolic phonon-polaritons in hexagonal-BN to highly concentrate mid-infrared light into a graphene pn-junction. We balance the interplay of the absorption, electrical and thermal conductivity of graphene via the device geometry. This approach yields remarkable device performance featuring room temperature high sensitivity (NEP of 82 pW/sqrt{{bf{Hz}}}) and fast rise time of 17 nanoseconds (setup-limited), among others, hence achieving a combination currently not present in the state-of-the-art graphene and commercial mid-infrared detectors. We also develop a multiphysics model that shows very good quantitative agreement with our experimental results and reveals the different contributions to our photoresponse, thus paving the way for further improvement of these types of photodetectors even beyond mid-infrared range.

Highlights

Integrating and manipulating the nano-optoelectronic properties of Van der Waals heterostructures can enable unprecedented platforms for photodetection and sensing
Novel nanooptoelectronic platforms can be attained by merging Hyperbolic phonon-polaritons (HPPs) functionalities with other 2D materials-based devices, such as graphene photodetectors governed by the photothermoelectric (PTE) effect
When light is polarized parallel to the bow-tie antenna axis, it excites its localized surface plasmon resonance (LSPR) spectrally located at λ ≈ 5–7 μm (Supplementary Figs. 1 and 2a)

Summary

Introduction

Integrating and manipulating the nano-optoelectronic properties of Van der Waals heterostructures can enable unprecedented platforms for photodetection and sensing. Novel nanooptoelectronic platforms can be attained by merging HPPs functionalities with other 2D materials-based devices, such as graphene photodetectors governed by the photothermoelectric (PTE) effect This mechanism generates a photoresponse in graphene pn-junctions[12,13,14,15,16,17,18,19] driven by a temperature gradient and Fermi level asymmetry across the channel. One of the limitations of these detectors is the low light absorption of graphene, especially for mid-IR frequencies where the photon energy becomes comparable to the typical doping level of graphene reaching the Pauli blocking regime[20,21] This is further exacerbated by the small photoactive area of graphene pnjunctions[16,22], limited by the cooling length of the hot carriers (0.5–1 μm)[13,14,22,23]. We embed hBN and graphene within metallic antennas in order to couple their plasmonic interactions with HPPs and achieve highly concentrated mid-IR light on a graphene pn-junction for sensitive and fast mid-IR photodetection

Methods

Results

Conclusion