Principal Investigator Moungi Bawendi
Electrical photodetection of IR light using QDs -- QD-based short-wave infrared (SWIR) detectors show promise as a low cost, solution processable alternative to InGaAs focal plane arrays. Our design involves QDs deposited in a photoconductive geometry on a modified integrated circuit, which allows for complicate fabrication of the circuit and electrodes prior to QD deposition. Using a single-pixel test structure, we have established a method to controllably tune the resistance of the QD film to match the capacitance of the circuitry.
We fabricate and study these devices both in our lab and in collaboration with the Bulovic group in the electrical engineering department at MIT.
Luminescent UV/IR dual-band photodetectors -- There is significant interest in developing dual band UV-IR photodetectors for communications, fire detection and military applications, however p-n junction photodetectors suffer from inherent limitations to sensitivity. The bright and tunable optical properties of IR emitting QDs can be using in a passive yet robust manner to improve the UV efficiencies of IR detectors via luminescent downshifting. By embedding QDs which absorb in the UV and emit in the IR regions of detector efficiency, we have effectively sensitized an InGaAs detector to UV radiation without hindering its exception IR performance, thereby creating a dual band detector. Infrared light incident on the bare detector is collected in the active region of the detector (gray box). Ultraviolet light is collected near the surface of the detector (yellow box) at low efficiency. With the addition of the QD layer, ultraviolet light is absorbed by the QDs and re-emitted in the infrared where it is collected in the active region of the detector. Due to the absorption profile of the QDs, the LDC layer absorbs most of the UV light, but is nearly transparent to infrared light.