Hybrid Device Architecture Using Plasmonic Nanoparticles, Graphene Quantum Dots, and Titanium Dioxide for UV Photodetectors

TLDR

Adding graphene quantum dots to TiO₂ provides an additional photon absorption pathway for UV detection. This study demonstrates a nanoscale UV photodetector architecture on sapphire (0001) that integrates plasmonic hybrid nanoparticles, graphene quantum dots, and TiO₂ for the first time. The device achieves enhanced performance by harnessing localized surface plasmon resonance–induced hot carriers and scattered photons from encapsulated HNPs, with photocurrent mechanisms investigated via FDTD simulation and energy band analysis. The hybrid GQDs/TiO₂/HNPs photodetector delivers a photocurrent of 1.58 × 10⁻⁵ A under 275 nm illumination at 10 V—about two orders of magnitude higher than bare TiO₂—while maintaining a dark current of ~1 × 10⁻¹⁰ A, yielding an excellent photo‑to‑dark ratio and millisecond‑scale rise/fall times, demonstrating high‑performance UV detection.

Abstract

In this work, a nanoscale device architecture is demonstrated for a UV photodetector application on sapphire (0001), incorporating the plasmonic hybrid nanoparticles (HNPs), graphene quantum dots (GQDs), and titanium oxide (TiO2) for the first time. The hybrid GQDs/TiO2/HNPs photodetector exhibits the photocurrent of 1.58 × 10–5 A under the 1.64 mW/mm2 of 275 nm illumination at 10 V, which is around two order increase from the bare TiO2 device. The proposed architecture demonstrates a low dark current of ∼1 × 10–10 A at 10 V and thus the device demonstrates an excellent photo to dark current ratio along with the improved rise and fall time on the order of several hundred millisecond. The enhanced performance of device architecture is attributed to the efficient utilization of localized surface plasmon resonance (LSPR) induced hot carriers as well as scattered photons from the plasmonic HNPs that are fully encapsulated by the photoactive TiO2 layers. Furthermore, the addition of GQDs on the TiO2 can offer an additional photon absorption pathway. The proposed hybrid architecture of GQDs/TiO2/HNPs demonstrates the integration of the photon absorption and carrier transfer properties of plasmonic HNPs, GQDs, and TiO2 for an enhanced ultraviolet (UV) photoresponse. The photocurrent enhancement mechanisms of the hybrid device architecture are thoroughly investigated based on the finite-difference time domain (FDTD) simulation along with the energy band analysis. This work demonstrates a great potential of the hybrid device architecture for high-performance UV photodetectors.