Molecularly-anchored single PbS quantum dots as resonant tunnelling transistors

The growing need for high-performance computing continues to drive improvement in circuit and device technologies, particularly with respect to speed and power efficiency. Device scaling remains the most effective strategy for meeting circuit performance requirements while reducing power consumption. Thanks to their solution processability, colloidal semiconductor quantum dots (QDs) are highly suitable for device miniaturisation as quantum information science platforms. Quantum mechanical effects must be carefully considered when designing nanometre-scale electronic devices (i.e., transistors) that incorporate a single QD. Here, we demonstrate a resonant tunnelling transistor (RTT) based on a single lead sulfide (PbS) QD anchored by a bidentate ligand molecule attached to heteroepitaxial spherical Au/Pt nanogap electrodes. Five negative differential resistances (NDRs) were observed at both positive and negative drain voltages in output characteristics, which could be attributed to the formation of a double-barrier "quantum well" structure with the strong Fermi level pinning of the discrete energy level of the QD to one electrode. Furthermore, these NDRs could be tuned by applying a gate electric field, which will become one of the keys for enabling quantum and neuromorphic electronics. This demonstration of single PbS-QD-based RTTs paves the way for sub-10 nm solution-processable quantum electronic devices.