Type-II superlattices for mid and long wavelength infrared photodetectors grown by metal-organic chemical vapour deposition

Brown, Richard 2024. Type-II superlattices for mid and long wavelength infrared photodetectors grown by metal-organic chemical vapour deposition. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Infrared devices play an important role in cutting edge applications including defence and security, gas detection, biomedical sensing, thermal imaging and 3D sensing. Antimony (Sb) based type-II superlattice (T2SL) materials are a strong candidate for next generation infrared technologies and are now considered as a viable alternative to the state-of-the-art mercury cadmium telluride (MCT). To date, molecular beam epitaxy (MBE) has been the prevailing technique for growing Sb containing structures. However, the commercial exploitation potential using metal-organic chemical vapor deposition (MOCVD) is highly attractive if material and device performance can be improved to close the gap with MBE results. This work focuses on the two main Sb based T2SLs, the InAs/GaSb T2SL and InAs/InAsSb T2SL. All the growth performed in this work was done via MOCVD. The growth and fabrication of long wave infrared InAs/GaSb T2SL photodetectors were investigated. Resulting in a InAs/GaSb T2SL nBn photodetector grown on an InAs substrate with a cutoff wavelength of 13.5 μm and a peak detectivity of 4.43x10^10 cm Hz^1/2 / W at 77K. The InAs/InAsSb T2SL was grown on GaSb substrates and fabricated with a cutoff wavelength of 5.5 μm and a peak detectivity of 1.14x10^12 cm Hz^1/2 / W at 77K. As well as growing the InAs/InAsSb T2SL on its native GaSb substrates. The InAs/InAsSb T2SL was grown on highly mismatched GaAs and Si substrates which have large economic benefits. An InAs/InAsSb PIN photodetector with a 100% cutoff wavelength of 5.25 μm was then successfully grown on the GaAs substrates. With a peak detectivity was 7.44x10^10 cm Hz^1/2 / W at 77K. The device performance in this work is competitive to current state of the art MBE results indicating that MOCVD can be considered a viable alternative to MBE for the growth of Sb based T2SL IR detectors at both mid and long Infrared wavelengths.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	MOCVD Metal-organic chemical vapor deposition T2SL Type-II superlattice InAs/InAsSb InAs/GaSb LWIR MWIR Infrared Detectors nBn PIN Antimony Sb Thermal imaging gas sensing 3D sensing Autonomous vehicles Thermography High quantum efficiency III/V on Si Epitaxy Surface passivation Dislocation filtering
Funders:	EPSRC
Date of First Compliant Deposit:	27 January 2025
Last Modified:	11 Feb 2025 12:03
URI:	https://orca.cardiff.ac.uk/id/eprint/175584

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