Response of Colloidal Quantum Dot Infrared Photodetectors to Modulated Optical Signals

In this paper, transfer function of a colloidal quantum dot infrared photodetector (CQDIP) is derived considering the system rate equations, to study the modulation response of a CQDIP. The presented transfer function models the system reaction to different modulation frequencies of input optical signals. Theoretical results obtained from our model are in excellent agreement with reported experimental data by Clifford et al., Konstantatos and Sargent, and Miri et al. Therefore, the validity of the model is proven for these reasons. Our analysis shows that this system provides a bandpass frequency response, converting optical signals to electrical signals with frequencies lying within its working region, and displaying transparent behavior beyond its working frequency region. This model helps photodetector designers selecting proper materials to fabricate suitable devices working in the desired frequency region with an eye toward the carrier lifetime in different intersubband energy levels.