Lecture
This lecture presents various examples of photoconductors, focusing on their characteristics and applications. The instructor discusses cadmium sulfide and cadmium selenide, which operate at room temperature and exhibit high gain, although they are toxic, limiting their use. The lecture continues with lead sulfide (PbS), which shows maximum sensitivity at 2.5 micrometers, and lead selenide (PbSe), which operates near room temperature with sensitivity around 4 micrometers. Indium antimonide (InSb) is introduced as a cooled detector with maximum sensitivity at 5.5 micrometers. The instructor also highlights research on monolayer MoS2 and graphene photodetectors, which work in the visible spectrum at room temperature, demonstrating high responsivity but slower response times. The trade-off between speed and gain is emphasized throughout the lecture. Finally, the instructor summarizes the performance metrics of various photoconductors, including quantum efficiency, internal gain, and noise characteristics, providing a comprehensive overview of their capabilities and limitations in infrared detection applications.