Low-temperature electroluminescence excitation mapping of excitons and trions in short channel monochiral carbon nanotube device

TL;DR

This study demonstrates stable electroluminescence from ultra short (9,8) carbon nanotube devices emitting in the telecom band, revealing mechanisms of exciton and trion emission control at low temperatures and nanoscale gaps.

Contribution

It provides the first electroluminescence excitation maps of short-channel carbon nanotube devices, elucidating carrier recombination and emission control mechanisms.

Findings

Stable electroluminescence at 10 nm gap size.

Excitonic and trionic emissions are gate-tunable.

Linewidths down to 2 meV at 4 K.

Abstract

Single walled carbon nanotubes as emerging quantum-light sources may fill a technological gap in silicon photonics due to their potential use as near infrared, electrically driven, classical or non-classical emitters. Unlike in photoluminescence, where nanotubes are excited with light, electrical excitation of single tubes is challenging and heavily influenced by device fabrication, architecture and biasing conditions. Here we present electroluminescence spectroscopy data of ultra short channel devices made from (9,8) carbon nanotubes emitting in the telecom band. Emissions are stable under current biasing and no quenching is observed down to 10 nm gap size. Low-temperature electroluminescence spectroscopy data also reported exhibits cold emission and linewidths down to 2 meV at 4 K. Electroluminescence excitation maps give evidence that carrier recombination is the mechanism for light generation in short channels. Excitonic and trionic emissions can be switched on and off by gate voltage and corresponding emission efficiency maps were compiled. Insights are gained into the influence of acoustic phonons on the linewidth, absence of intensity saturation and exciton exciton annihilation, environmental effects like dielectric screening and strain on the emission wavelength, and conditions to suppress hysteresis and establish optimum operation conditions.