Effect of compressive strain on the performance of p-type quantum well infrared photodetectors

A detailed study of the performance of compressively strained p-type III-V quantum well infrared photodetectors (p-QWIPs) is presented in this work. Three device structures composed of InGaAs/GaAs, InGaAs/AlGaAs, and InGaAs/AlGaAs/GaAs for normal incidence absorption have been fabricated and analyzed, with the results being compared with similar reported unstrained p-QWIPs. In all three QWIP structures, the quantum well layers are under biaxial compressive strain ranging from -0.8 to 2.8 percent, while the barrier layers are lattice matched to the substrate. The detection peaks of the quantum well infrared photodetectors ranged from 7.4 micrometers to 10.4 micrometers . The detectors utilized the bound-to-continuum, bound-to-quasi- bound, and step bound-to-miniband intersubband transitions for infrared detection. The results showed that responsivities of up to 90 mA/W and detectivities from 109 to over 1010 cm (root) Hz/W are achieved under moderate applied bias and at reasonable operating temperatures, demonstrating the viability of the strained layer p-doped quantum well infrared photodetectors for staring focal plane array applications.