# Observation of a Fano Resonance at 92 meV (13.5 µm) in Al0.2Ga0.8N/GaN-Based Quantum Cascade Emitters

## TL;DR

The paper reports the observation of a Fano resonance in a specific quantum cascade structure made of Al0.2Ga0.8N/GaN.

## Contribution

The study demonstrates the first observation of a Fano resonance in Al0.2Ga0.8N/GaN-based quantum cascade emitters.

## Key findings

- A Fano resonance was observed at 92 meV (13.5 µm) in the quantum cascade structure.
- The resonance arises from the interference between a narrow LO-phonon peak and a broad inter-subband emission.
- The asymmetric Fano line shape was confirmed through electro-luminescence measurements.

## Abstract

We report on asymmetrically shaped Fano resonances in Al0.2Ga0.8N/GaN-based quantum cascade structures. In order to observe this type of resonance in electro-luminescence, a spectrally narrow feature must interact with a broad, quasi-continuous emission. While the narrow waveform is provided by the GaN-based LO-phonon at 92 meV (13.5 µm, 741 cm−1), the broad peak consists of overlapping inter-subband transitions between several higher-order excited states ranging from 80 to 300 meV and the ground state. Through the interference of these spectrally dissimilar peaks, a typical, asymmetric Fano line shape is generated.