Mechanism of IR Photoresponse in Nanopatterned InAs/GaAs Quantum Dot p-i-n Photodiodes

We report on measurements of the infrared photo-response of InAs-based p-i-n diodes in the spectral region above 1.8 ?m. These photodiodes were fabricated from arrays of InAs quantum dots grown in nano-patterned template structures using a combination of block copolymer lithography and molecular beam epitaxy. The devices studied were comprised of a single layer of quantum dots. The temperature dependence of the current versus voltage for these devices is presented and discussed. Finally, a model is presented that can explain the key characteristics of the measured current versus voltage curves as a function of both temperature and applied electric field.