Indium Antimonide Based Mid-Infrared Optoelectronics

When?

Thursday 15 March 2012, 13:00 to 14:00

Where?

ATI seminar room - 02ATI02

Open to:

Students, Staff

Speaker:

Geoff Nash, College of Engineering, Mathematics and Physical Sciences at the University of Exeter

In this talk I will review work over the last few years aimed at developing a range of midinfrared (3-7 m) optoelectronics based on indium antimonide. Low cost, efficient midinfrared components are required for applications such as gas sensing, free space optical communication, healthcare and missile countermeasures.
In the first part of the talk I will describe the development of LEDs and detectors for gas sensing. Current infrared sensors use incandescent sources and pyroelectric or thermopile detectors, which have several disadvantages including slow response time, limited wavelength range (due to the glass envelope of the source), limited lifetimes due to the fragility of the source, relatively high power consumption, and a requirement for explosion proof housings to prevent the source from igniting flammable gases that may be present. The replacement of these thermal sources with uncooled semiconductor light-emitting diodes (LEDs) and photodetectors would therefore lead to sensors with comparable sensitivity, which is likely to increase dramatically as the components are improved, but at reduced cost, with real time response, reduced power consumption, and a much wider wavelength sensitivity range. Some of the component technology developed was licensed to Gas Sensing Solutions (http://www.gassensing.co.uk/), who now manufacture sensors incorporating these devices.

In the second part of the talk I will describe research into the development of laser diodes using the aluminium-gallium-indium-antimonide (AlxGayIn1-x-ySb) material system, which offers great promise for efficient laser diode operation across the 3 to 5ƒÝm wavelength range. It offers an excellent compromise between the requirements for good electronic and optical confinement and those for low series resistance. In addition, the use of an active region comprising compressively strained Type-I quantum wells (QWs) is predicted to lead to increased gain, which leads to lower threshold current densities and hence reduced nonradiative Auger recombination. In this talk a review of recent progress in the development of this material system will be given, including the demonstration of multi-quantum well samples exhibiting photoluminescence up to room temperature, and laser diodes operating up to 219 K.