Ultra-thin van der Waals crystals as semiconductor quantum wells

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Electron quantization in quantum wells is crucial for advanced electronics like transistors and lasers.
• This control has not been extensively explored in two-dimensional (2D) materials.
• Van der Waals heterostructures offer a promising platform for novel electronic properties.

Purpose of the Study:

• To explore electron quantization control in 2D materials using van der Waals heterostructures.
• To investigate the use of exfoliated crystal thickness for controlling quantum well dimensions.
• To enable development of atomically thin infrared and terahertz light sources.

Main Methods:

• Utilized few-layer semiconductor Indium Selenide (InSe) van der Waals heterostructures.
• Controlled quantum well dimensions by varying the thickness of exfoliated InSe crystals.
• Studied resonance features in tunnelling current, photoabsorption, and light emission spectra.

Main Results:

• Achieved precise control over subband energies and uniformity in few-layer InSe.
• Demonstrated extremely high-quality electronic transport in these engineered systems.
• Revealed the complete subband structure through various spectroscopic methods.

Conclusions:

• Thickness control in van der Waals heterostructures provides a new route for electron quantization.
• These systems exhibit excellent electronic transport properties suitable for advanced devices.
• Potential for creating novel, atomically thin infrared and terahertz light sources based on intersubband transitions.