Flexible hybrid graphene/a-Si:H multispectral photodetectors

TL;DR

This paper presents flexible, multispectral photodetectors using graphene electrodes that significantly enhance UV response, tunable wavelength detection, and can be fabricated on flexible substrates, advancing applications in spectroscopy and biomedical fields.

Contribution

The integration of large-area CVD graphene electrodes into amorphous silicon photodetectors introduces enhanced UV response, tunable spectral detection, and device flexibility, representing a novel approach in multispectral photodetector design.

Findings

440% enhancement in UV spectral response with graphene electrodes

Responsivity tunable from 320 nm to 510 nm via bias voltage

Flexible diodes on polyimide substrates with bilayer graphene

Abstract

We report on the integration of large area CVD grown single- and bilayer graphene transparent conductive electrodes (TCEs) on amorphous silicon multispectral photodetectors. The broadband transmission of graphene results in 440% enhancement of the detectors' spectral response in the ultraviolet (UV) region at {\lambda} = 320 nm compared to reference devices with conventional aluminum doped zinc oxide (ZnO:Al) electrodes. The maximum responsivity of the multispectral photodetectors can be tuned in their wavelength from 320 nm to 510 nm by an external bias voltage, allowing single pixel detection of UV to visible light. Graphene electrodes further enable fully flexible diodes on polyimide substrates. Here, an upgrade from single to bilayer graphene boosts the maximum photoresponsivity from 134 mA $W^{-1}$ to 239 mA $W^{-1}$. Interference patterns that are present in conventional TCE devices are suppressed as a result of the atomically thin graphene electrodes. The proposed detectors may be of interest in fields of UV/VIS spectroscopy or for biomedical and life science applications, where the extension to the UV range can be essential.