Near infrared photodetectors based on PbS colloidal quantum dots

Colloidal Quantum Dots (CQD), due to their extremely large optical absorption coefficient and tunability of the absorption bands, are very promising for the realization of photodetectors. PbS quantum dots, in particular, can be effectively employed as a material for near infrared photodetectors with sensitivity peaks ranging from 1 to 2 mu m. CQD photodetectors, nevertheless, present still many unsolved issues when it comes to fast detection and noise performance. Thanks to the recent advances in CQD material synthesis and treatment, photodetectors achieved unprecedented performance but the aforementioned issues could still not be fully addressed. Concerning photodetectors, however, material quality is only the starting point for the realization of performing devices: CQD technology came to the point where an engineering approach is needed in order to fully comprehend the behavior of the photodetectors, to define proper strategies for the enhancement of their performance and introduce them in practical applications. In this work we analyze the optical and electrical characteristics of PbS CQD near infrared photodetectors fabricated on SiO2 substrate and demonstrate how even a simple, fully passive readout circuit topology could be employed in order to obtain a dramatic enhancement of the characteristics of the devices.