A Thermal-electrically Cooled Longwave (8-12 um) Quantum Dot Infrared Photodetector with High Quantum Efficiency

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Intellectual Property

ID:		UML 06-14
IP Type:		Licensable Technology
Title:		A Thermal-electrically Cooled Longwave (8-12 um) Quantum Dot Infrared Photodetector with High Quantum Efficiency
Inventor:		Xuejun Lu
Summary:		The researchers have conceived of a thermal-electrically cooled longwave (8-12µm) Quantum Dot infrared photodetector with high quantum efficiency. Essentially, the device is an infra-red (IR) photodetector demonstrating four orders of magnitude less noise than conventional photodetectors cooled to similar temperatures. At 180K, its measured noise level is similar to other devices at 77K. The invention has two novel aspects: 1) based on a novel two-photon sequential absorption (TPSA) process in InAs QD heterostructures to increase the energy barrier from 130meV to 260meV, based on the nonlinear TPSA process. This suppresses substantially the thermal-excited dark current level; and 2) uses a resonant cavity to increase the quantum efficiency and reduce background noise. The working mechanism of the invention uses a two-photon excitation system in a base of five layers of InAs/AlxGa1-xAs. With the use of quantum dots, the first infrared photon excites an electron into a conduction band (along with other electrons that are moved into the conduction band from general thermal excitation); the second photon moves the electron into a higher conduction band, where there is no noise. The invention incorporates an already-known mechanism for increasing the absorption of IR radiation via a set of mirror-like structures that reflect radiation within the device until it is absorbed; and these structures include Bragg gratings at the bottom of the device.
Tech Type:		Electrical Engineering
URL:		http://www.uml.edu/cvip
Contact:		Susu Wong, 978 934 4722, susu_wong@uml.edu
Organization:		University of Massachusetts Lowell

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