研究目的
To circumvent the detrimental effects arising from the progressively increasing dot-size in vertically coupled heterostructures of InAs Quantum-dot infrared photodetectors.
研究成果
The proposed growth strategy successfully mitigates the issues of inhomogeneous dot size distribution and non-uniform strain propagation in vertically coupled QD ensembles. The incorporation of an In0.15Ga0.85As strain reducing layer further enhances the optical and structural properties, leading to improved device performance with high responsivity and detectivity at room temperature.
研究不足
The study focuses on InAs/GaAs quantum dot systems and may not be directly applicable to other material systems. The growth strategy requires precise control of monolayer coverage and spacer layer thickness, which may be challenging to replicate.
1：Experimental Design and Method Selection:
The study involves the epitaxial growth of InAs Quantum-dot infrared photodetectors using a molecular beam epitaxy (MBE) system. The growth strategy includes controlling the monolayer coverage for dot layers to maintain constant overgrowth percentage and dot sizes.
2：Sample Selection and Data Sources:
Semi-insulating GaAs substrates with (100) orientation were used. The samples include conventionally coupled heterostructures and those with proposed growth strategies with and without a strain reducing layer (SRL).
3：List of Experimental Equipment and Materials:
Riber SYS14020 Epineat III-V MBE system, Rigaku Smart Lab double-axis diffractometer for HR-XRD, JEOL JEM 2010F electron microscope for X-TEM, and a 532 nm diode-pump solid-state laser for PL measurements.
4：Experimental Procedures and Operational Workflow:
The growth process involves depositing a GaAs buffer, AlAs etch stop layer, and P-type GaAs bottom contact, followed by InAs QD layers with GaAs spacer layers. The samples are characterized using PL, PLE, HR-XRD, and X-TEM.
5：Data Analysis Methods:
The optical and structural properties are analyzed through PL and PLE spectra, HR-XRD rocking curves, and X-TEM images. Device performance is evaluated through spectral response, responsivity, and detectivity measurements.
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