Infrared Photodetectors at Medium and Long Wavelengths

Prof. (Dr.) N. R. Das
Institute of Radio Physics and Electronics, University of Calcutta,
92 A.P.C. Road, Kolkata-700009, West Bengal, India

Abstract -  
         Infrared photo detectors find applications in various fields, such as, thermal imaging, non-invasive medical diagnosis, secured communication, etc. Though the infrared photo detectors have been studied for a long time, there has been an increased interest in this area because of the emerging applications at medium and long wavelengths. It has now become feasible to engineer some basic properties of semiconductors, thanks to the advancement of material and growth technology of semiconductors.  The talk starts with the working principles of semiconductor infrared  photo detectors along with different absorption mechanisms. The discussion is focused mainly on the quantum (photon) detector type infrared photo detectors. With special mention of intersub band transition in semiconductor nanostructures, ‘Figures of merit’ and the performance of quantum well or quantum dots based infrared photo detectors and quantum dot infrared photo detectors will also be discussed.