Current Crowding in a High-Efficiency Black Phosphorus Light-Emitting Diode Using a Reflective Back Contact.
Julien Brodeur1, Éloïse Rahier1, Mathieu Chartray-Pronovost2
1Department of Engineering Physics, Polytechnique Montréal, Montréal H3T 1J4, Canada.
Nano Letters
|July 18, 2025
Summary
We developed a high-performance mid-infrared (MIR) light-emitting diode (LED) using black phosphorus (b-P) and n-type Molybdenum disulfide (MoS2). This novel 2D material heterojunction achieves record efficiencies for MIR light emission.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Optoelectronics
Background:
- Mid-infrared (MIR) light-emitting diodes (LEDs) are crucial for various applications, including sensing and communication.
- Developing efficient and high-performance MIR LEDs based on novel materials remains a significant challenge.
Purpose of the Study:
- To demonstrate a high-performance MIR LED utilizing a black phosphorus (b-P)/n-type Molybdenum disulfide (MoS2) heterojunction.
- To investigate the underlying physics governing the device performance through experimental characterization and finite-element simulations.
Main Methods:
- Fabrication of a b-P/n-MoS2 heterojunction LED with enhanced light extraction features (gold back contact, Re-doped n-MoS2).
- Experimental characterization of the LED's performance, including external quantum efficiency (EQE) and radiant power density at room temperature and 77 K.
- Finite-element simulations to model device physics, including carrier transport mechanisms and current crowding effects.
Main Results:
- Achieved a peak MIR external quantum efficiency (EQE) of (1.6 ± 0.2)% at room temperature and a record (7.0 ± 0.5)% EQE at 77 K.
- Demonstrated a maximum radiant power density of (108 ± 8) W/cm².
- Simulations revealed the significance of phonon-assisted band-to-band tunneling and carrier velocity saturation, and explained high ideality factors due to current crowding and device geometry.
Conclusions:
- Established a new high-performance b-P LED architecture for MIR light emission.
- Provided crucial insights into the physics of MIR sources based on two-dimensional (2D) materials.
- The b-P/n-MoS2 heterojunction offers a promising platform for advanced optoelectronic devices.
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