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Optical anisotropy in self-assembled InAs nanostructures grown on GaAs high index substrate
Journal of Applied Physics
|March 8, 2012
Summary
This study explores InAs nanostructures on various GaAs substrates. InAs quantum dots on GaAs(115)A show superior optical properties, with quantum strings identified on other orientations.
Area of Science:
- Materials Science
- Solid State Physics
- Nanotechnology
Background:
- Semiconductor nanostructures, specifically Indium Arsenide (InAs) quantum dots (QDs), are crucial for advanced electronic and optoelectronic devices.
- Growth of these nanostructures on high-index substrates like Gallium Arsenide (GaAs) presents unique challenges and opportunities for property tuning.
Purpose of the Study:
- To investigate the optical properties of InAs self-assembled nanostructures grown on different high-index GaAs substrates (GaAs(11N)A, N=3-5).
- To identify and characterize different nanostructure formations, such as quantum dots (QDs) and quantum strings (QSTs).
- To elucidate the formation mechanisms of these nanostructures under specific growth conditions.
Main Methods:
- Molecular beam epitaxy (MBE) for growing InAs nanostructures on GaAs(11N)A substrates.
- Photoluminescence (PL) spectroscopy to analyze optical properties and emission characteristics.
- Polarized photoluminescence to identify emission sources.
- Theoretical modeling using the 3D Schrödinger equation and finite element method, incorporating strain and piezoelectric effects.
Main Results:
- InAs quantum dots grown on GaAs(115)A exhibited better optical properties compared to those on GaAs(113)A and GaAs(114)A.
- An additional emission peak at 1.39 eV, attributed to quantum strings (QSTs), was observed in samples grown on GaAs(114)A and GaAs(113)A.
- This QST emission was stable even at low power densities.
- Theoretical calculations supported the experimental observations and helped distinguish emission peaks.
Conclusions:
- The GaAs(115)A substrate is optimal for growing high-quality InAs quantum dots with desirable optical properties.
- Quantum strings are a distinct nanostructure formation on high-index GaAs substrates, contributing a specific emission peak.
- The formation of both QDs and QSTs is influenced by piezoelectric effects and surface equilibrium on these high-index substrates.
