Resonant Light Emission from Graphene/Hexagonal Boron Nitride/Graphene Tunnel Junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optoelectronics

Background:

• Single-layer graphene lacks a band gap, limiting its use in light-emitting devices.
• Controlled stacking of graphene layers can overcome this limitation.
• Graphene's unique Dirac cone band structure is key to novel electronic and optical properties.

Purpose of the Study:

• To demonstrate twist-controlled resonant light emission from graphene/hexagonal boron nitride (h-BN)/graphene tunnel junctions.
• To investigate the influence of crystallographic alignment on light emission properties.
• To explore the potential of these structures for on-chip optoelectronic applications.

Main Methods:

• Fabrication of graphene/h-BN/graphene tunnel junctions with varying twist angles.
• Optical and electrical characterization of the tunnel junctions.
• Theoretical modeling to explain the observed light emission mechanisms.

Main Results:

• Observed light emission from graphene/h-BN/graphene tunnel junctions, irrespective of alignment.
• Pronounced resonant features in optical and electrical characteristics for twist angles below 3°.
• Rapid vanishing of resonant features for twist angles greater than 3°.
• Spectral tuning of the resonant peak within the near-infrared range by over 0.2 eV.

Conclusions:

• Photon-assisted momentum conserving electron tunneling explains the resonant light emission.
• Twist-controlled graphene/h-BN/graphene tunnel junctions exhibit tunable near-infrared emission.
• These structures are promising candidates for future on-chip optoelectronic devices.