Highly-efficient electrically-driven localized surface plasmon source enabled by resonant inelastic electron tunneling

Haoliang Qian,Shilong Li,Ching-Fu Chen,Fanglin Tian,Zhaowei Liu,Su-Wen Hsu,Andrea R Tao

doi:10.1038/s41467-021-23512-2

Haoliang Qian, Shilong Li + Show 5 more

Open Access

https://doi.org/10.1038/s41467-021-23512-2

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Abstract

On-chip plasmonic circuitry offers a promising route to meet the ever-increasing requirement for device density and data bandwidth in information processing. As the key building block, electrically-driven nanoscale plasmonic sources such as nanoLEDs, nanolasers, and nanojunctions have attracted intense interest in recent years. Among them, surface plasmon (SP) sources based on inelastic electron tunneling (IET) have been demonstrated as an appealing candidate owing to the ultrafast quantum-mechanical tunneling response and great tunability. However, the major barrier to the demonstrated IET-based SP sources is their low SP excitation efficiency due to the fact that elastic tunneling of electrons is much more efficient than inelastic tunneling. Here, we remove this barrier by introducing resonant inelastic electron tunneling (RIET)—follow a recent theoretical proposal—at the visible/near-infrared (NIR) frequencies and demonstrate highly-efficient electrically-driven SP sources. In our system, RIET is supported by a TiN/Al2O3 metallic quantum well (MQW) heterostructure, while monocrystalline silver nanorods (AgNRs) were used for the SP generation (localized surface plasmons (LSPs)). In principle, this RIET approach can push the external quantum efficiency (EQE) close to unity, opening up a new era of SP sources for not only high-performance plasmonic circuitry, but also advanced optical sensing applications.

Highlights

On-chip plasmonic circuitry offers a promising route to meet the ever-increasing requirement for device density and data bandwidth in information processing
The calculated electronic subband diagram of this metallic quantum well (MQW) is given in Supplementary Note 2, which shows that there are seven discrete states provided by the MQW owing to its high quantum well (QW) barrier (~8 eV), allowing one to realize resonant inelastic electron tunneling (RIET) at visible/NIR frequencies, and to tune it by a large range of external voltages
When the resonant electron state |5〉 of the middle MQW is aligned with the Fermi level of the TiN positive electrode by increasing the bias voltage (Fig. 1b), RIET processes start—i.e., electrons in the ITO negative electrode tunnel through this MQW junction inelastically by coupling to a plasmonic mode of energy hν supported by the AgNRs on top of the junction (Fig. 1a, b), where h is the Planck constant and ν is the frequency

Summary

Introduction

On-chip plasmonic circuitry offers a promising route to meet the ever-increasing requirement for device density and data bandwidth in information processing. Source at the visible/NIR frequencies in metallic quantum well (MQW)-based tunnel junctions.

Results

Conclusion