Nano-imaging of intersubband transitions in van der Waals quantum wells

TL;DR

This paper reports the first experimental observation of intersubband transitions in van der Waals quantum wells, demonstrating their potential for advanced optoelectronic devices with atomically sharp interfaces and high design flexibility.

Contribution

It introduces van der Waals quantum wells for intersubband transitions and demonstrates near-field control at nanometer scale, overcoming limitations of traditional semiconductor heterostructures.

Findings

First experimental observation of intersubband transitions in van der Waals quantum wells

Near-field probing achieves nanometer-scale spectral resolution and electrostatic control

Potential for new photodetectors, LEDs, and lasers with atomically sharp interfaces

Abstract

The science and applications of electronics and optoelectronics have been driven for decades by progress in growth of semiconducting heterostructures. Many applications in the infrared and terahertz frequency range exploit transitions between quantized states in semiconductor quantum wells (intersubband transitions). However, current quantum well devices are limited in functionality and versatility by diffusive interfaces and the requirement of lattice-matched growth conditions. Here, we introduce the concept of intersubband transitions in van der Waals quantum wells and report their first experimental observation. Van der Waals quantum wells are naturally formed by two-dimensional (2D) materials and hold unexplored potential to overcome the aforementioned limitations: They form atomically sharp interfaces and can easily be combined into heterostructures without lattice-matching restrictions. We employ near-field local probing to spectrally resolve and electrostatically control the intersubband absorption with unprecedented nanometer-scale spatial resolution. This work enables exploiting intersubband transitions with unmatched design freedom and individual electronic and optical control suitable for photodetectors, LEDs and lasers.