Quantum-dot infrared photodetectors: Status and outlook

This paper reviews the present status Mid possible future developments of quantum-dot infrared photodetectors (QDIPs). At the beginning the paper summarizes the fundamental properties of QDIPs. Next, an emphasis is put on their potential developments. Investigations of the performance of QDIPs as compared to other types of infrared photodetectors are presented. A model is based on fundamental performance limitations enabling a direct comparison between different infrared material technologies. It is assumed that the performance is due to thermal generation in the active detector's region. In comparative studies, the HgCdTe photodiodes, quantum well infrared photodetectors (QWIPs). type-II superlattice photodiodes, Schottky barrier photoemissive detectors, doped silicon detectors, and high-temperature superconductor detectors are considered. Theoretical predictions indicate that only type-II superlattice photodiodes and QDIPs are expected to compete with HgCdTe photodiodes. QDIPs theoretically have several advantages compared with QWIPs including the normal incidence response, lower dark current, higher operating temperature, higher responsivity and detectivity. The operating temperature for HgCdTe detectors is higher than for other types of photon detectors. It is also shown, that BLIP temperature of QDIP strongly depends on nonuniformity in the QD size. Comparison of QDIP performance with HgCdTe detectors gives clear evidence that the QDIP is suitable for high operation temperature. It can be expected that improvement in technology and design of QDIP detectors will make it possible to achieve both high sensitivity and fast response useful for practical application at room temperature FPAs. Comparison of theoretically predicted and experimental data indicates that, as so far, the QDIP devices have not fully demonstrated their potential advantages and are expected to posses the fundamental ability to achieve higher detector performance. Poor QDIP performance is generally linked to nonoptimal band structure and controlling the QDs size and density (nonuniformity in QD size) (C) 2008 Elsevier Ltd. All rights reserved.