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Band structure engineering in strain-free GaAs mesoscopic systems
Vanessa Orsi Gordo1, Leonarde N Rodrigues2,3, Floris Knopper4,5
1Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, 13083-859, Campinas, São Paulo, Brazil.
Nanotechnology
|March 7, 2020
Summary
By tuning the band alignment in GaAs/AlGaAs structures, researchers achieved longer carrier lifetimes and enhanced optical emission from mesoscopic structures. This control over X-Γ band mixing optimizes carrier injection and light extraction.
Area of Science:
- Semiconductor physics
- Optoelectronics
- Materials science
Background:
- Investigating optical properties of mesoscopic GaAs/AlGaAs structures (MGS) coupled to quantum wells (QWs).
- Understanding the impact of Al content (x) on band alignment and optical emission.
Purpose of the Study:
- To demonstrate how controlling band crossover (X-point and Γ-point) in AlGaAs influences carrier lifetimes and MGS emission.
- To explore the manipulation of recombination rates and carrier injection efficiency in MGS.
Main Methods:
- Fabrication and optical characterization of strain-free MGS coupled to QWs with varying Al content.
- Photoluminescence (PL) spectroscopy to analyze emission properties.
- Time-resolved measurements to study carrier dynamics and recombination processes.
Main Results:
- Type-I to type-II band alignment transition observed for x ≥ 0.50, quenching QW emission and enhancing MGS emission via carrier injection.
- Spectral filtering of MGS emission observed for x ≥ 0.70 due to X-Γ band crossover.
- Two recombination processes identified in MGS: a fast component dependent on MGS X-Γ mixing (0.3–2.5 ns) and a slow component dependent on QW X-Γ mixing.
Conclusions:
- Quenching QW emission by controlling band crossover leads to long carrier lifetimes and enhanced MGS optical emission.
- Independent tuning of X-Γ mixing in QW and MGS states allows manipulation of MGS recombination rates.
- Efficient carrier injection and light extraction achieved by optimizing X-Γ mixing.
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