Long-Wavelength Quantum Well Infrared Photodetectors

A maiority o f IR sensors used for imaging arrays operating in the long-wavelength IR region between 8 p m 1 2 pm are based on mercury cadmiumiell;ride(~&~e).?his mater~arsystem isunable t&isfy all the requimncntsimposed by modmapvlicat~ons. Structuddifficultiesduetopooruniformi~, high defcctdensities, and weak bond &ngthbcaused~~fulties in manufacturing large IR focal planearmy camcras~~san lternative. quanturnwll infrared phaodctectors(QWIPs) utilising intersubband absorption between gallium arsenide (GaAs) wellsandsluminiumealliumarsenide~AIG~s) barriers were ~erfected. These OWlPs wssess better uniformitv in comparison lo H g d T e detectors, i d QWIP imaging an & have recently ~;ecom~commere~ally availabl; However, the ~ponsiviryofGoAslAICoAsQWlPs ~sstl l l lower than /lgCdTedetccton. To furthn improve the raponsiviry ofQWlPdetcctors, QWlPs with wcllsor barriers ofGalnAsP Instead ofAIGhAs have been developed. Results ofQWlPs msde from thematmal systems GaAsSalnP. GalnAs(P)NnP. (A1)GalnAsllnP. and (;alnAsl AllnAs hav; been discussed