研究目的
Investigating the in-plane electrical transport properties of midwave and longwave infrared InAs/GaSb type-II superlattices grown on GaAs substrates to understand their conduction behavior and scattering mechanisms.
研究成果
The InAs/GaSb T2SLs grown on GaAs substrates using IMF technique exhibit high structural quality. MWIR T2SLs show a change from p-type to n-type conduction with temperature, dependent on growth temperature due to defect levels, while LWIR T2SLs are n-type throughout. Interface roughness scattering is dominant at low temperatures in LWIR T2SLs. These insights improve understanding of T2SL properties for enhancing infrared photodetector performance.
研究不足
The study is limited to specific superlattice configurations (MWIR and LWIR) and growth conditions on GaAs substrates. The influence of the p-type GaSb buffer layer on Hall measurements may affect results, though it is noted to be negligible for n-type conduction. The findings are specific to the materials and techniques used and may not generalize to other systems or growth methods.
1：Experimental Design and Method Selection:
The study involves growing InAs/GaSb type-II superlattices (T2SLs) on GaAs substrates using molecular beam epitaxy (MBE) with an interfacial misfit array (IMF) technique to reduce lattice mismatch. Special shutter sequences are used to form InSb-like and GaAs-like interfaces for strain compensation. High-resolution X-ray diffraction (HRXRD) and Hall effect measurements are employed to characterize structural and electrical properties.
2：Sample Selection and Data Sources:
Samples include MWIR (10 ML InAs/10 ML GaSb) and LWIR (24 ML InAs/7 ML GaSb) T2SLs grown on semi-insulating GaAs (001) substrates. MWIR samples are grown at different temperatures (330, 390, 400 °C) to study temperature effects, while LWIR is grown at 390 °C.
3：List of Experimental Equipment and Materials:
Equipment includes a RIBER Compact 21-DZ MBE system with effusion cells for In and Ga, valved cracked cells for As and Sb, RHEED system for in-situ monitoring, PANalytical X'Pert HRXRD system with Cu Kα1 radiation, and ECOPIA Hall effect measurement system with Van der Pauw method. Materials include GaAs substrates, GaSb buffer layers, and InAs/GaSb superlattices.
4：Experimental Procedures and Operational Workflow:
Deoxidize GaAs substrates at 610 °C, deposit a 250-nm GaAs layer at 585 °C, grow a 1-μm GaSb buffer layer using IMF at 440 °C, then grow T2SLs at specified temperatures with controlled shutter sequences. Monitor growth with RHEED. Perform HRXRD to assess structural quality and Hall effect measurements from 80-300 K with a magnetic field of 0.4 T on 6x6 mm2 samples with indium contacts.
5：4 T on 6x6 mm2 samples with indium contacts.
Data Analysis Methods:
5. Data Analysis Methods: Use Epitaxy software for HRXRD simulation to determine superlattice period and composition. Analyze Hall effect data to extract carrier concentration, mobility, and resistivity, applying Arrhenius law to find activation energies and identify scattering mechanisms.
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