InGaAs/InGaP quantum-dot infrared photodetector with a high detectivity

Quantum-dot infrared photodetectors (QDIPs) have recently been considered as strong candidates for numerous applications such as night vision, space communication, gas analysis and medical diagnosis involving middle and long wavelength infrared (MWIR and LWIR respectively) operation. This is due to their unique properties arising from their 3-dimensional confinement potential that provides a discrete density of states. They are expected to outperform quantum-well infrared photodetectors (QWIPs) as a consequence of their natural sensitivity to normal incident radiation, their higher responsivity and their higher-temperature operation. So far, most of the QDIPs reported in the literature were based on the InAs/GaAs system and were grown by molecular beam epitaxy (MBE). Here, we report on the growth of a high detectivity InGaAs/InGaP QDIP grown on a GaAs substrate using low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The peak photoresponse was around 4.7μm and the peak responsivity had a value of 1.2 A/W at a peak detection bias of -0.9V at 77K. A noise current of 3.3×10 -14 A at - 0.9V bias yielded a specific peak detectivity of 1.2×10 12 cmHz 1/2 /W at 77K. Peak responsivity and specific peak detectivity of 190.5mA/W and 8.3×10 10 cmHz 1/2 /W were still measured at 120K for a peak detection bias of -0.6V. A BLIP temperature of 200K was determined with a 45° field of view and a 300K background.