# Electrical detection of hyperbolic phonon-polaritons in heterostructures of graphene and boron nitride

## TL;DR

This paper demonstrates an innovative heterostructure platform combining graphene and boron nitride to electrically detect hyperbolic phonon-polaritons, enhancing mid-infrared photodetector responsivity and tunability for high-resolution imaging.

## Contribution

It introduces a novel heterostructure-based method for electrical detection of HPPs, integrating hyperbolic phonon-polaritons with graphene for improved mid-infrared photodetection.

## Key findings

- Electrical detection of HPPs via graphene pn-junctions.
- Enhanced responsivity in mid-infrared photodetectors.
- Tunable frequency selectivity enabled by HPPs.

## Abstract

Light properties in the mid-infrared can be controlled at a deep subwavelength scale using hyperbolic phonons-polaritons (HPPs) of hexagonal boron nitride (h-BN). While propagating as waveguided modes HPPs can concentrate the electric field in a chosen nano-volume. Such a behavior is at the heart of many applications including subdiffraction imaging and sensing. Here, we employ HPPs in heterostructures of h-BN and graphene as new nano-optoelectronic platform by uniting the benefits of efficient hot-carrier photoconversion in graphene and the hyperbolic nature of h-BN. We demonstrate electrical detection of HPPs by guiding them towards a graphene pn-junction. We shine a laser beam onto a gap in metal gates underneath the heterostructure, where the light is converted into HPPs. The HPPs then propagate as confined rays heating up the graphene leading to a strong photocurrent. This concept is exploited to boost the external responsivity of mid-infrared photodetectors, overcoming the limitation of graphene pn-junction detectors due to their small active area and weak absorption. Moreover this type of detector exhibits tunable frequency selectivity due to the HPPs, which combined with its high responsivity paves the way for efficient high-resolution mid-infrared imaging.