High performance InGaAs/InGaP quantum dot infrared photodetector achieved through doping level optimization

We report an InGaAs/InGaP/GaAs quantum dot infrared photodetector grown by metalorganic chemical vapor deposition with detectivity of 1.3x10 11 cmHz1/2/W at 77K and 1.2x10 10 cmHz 1/2 /W at 120K. Modeling of the Quantum dot energy levels showed us that increased photoresponse could be obtained by doping the quantum dots to 4 electrons per dot instead of the usual 2 electrons per dot. This happens because the primary photocurrent transition is from the first excited state to a higher excited state. Increasing the quantum doping in our device yielded significant responsivity improvement and much higher detectivity as a result. This paper discusses the performance of this higher doping device and compares it to our previously reported device with lower doping.