Progress and prospects for quantum dots in a well infrared photodetectors

Over the past fifteen years, there has been significant interest in developing intersubband quantum dot (QD) detectors for the mid-(MWIR) and long-wave infrared (LWIR) regimes. This class of detectors is generally referred to as quantum dot infrared photodetectors, or QDIPs. At present, one of the leading technologies is that of the quantum dots-in-a-well infrared photodetector, called a DWELL-IP or just a DWELL detector. The DWELL name comes from the active region's structure, which consists of a layer of quantum dots imbedded in (or in some cases grown on) a quantum well. This dot/well combination is similarly surrounded by a barrier material. Here, we identify the major players and their contributions to the evolution of the DWELL-IP. While this dot/well/barrier material combination originally consisted of InAs/InGaAs/GaAs, the materials used has widened in recent years. This paper reviews the progress to date for this quickly advancing field. Some of these advancements have come from the additional focus that has been brought to bear on the physical understanding and experimental mechanics of the structure itself. Explorations into the multi-spectral nature of these detectors have also created unique applications for these detectors. This type of QDIP is now becoming the dominant detector of its class and is quickly heading for parity with quantum well infrared photodetectors (QWIPs) that are presently commercially dominant. Given the potential utility of the infrared spectrum for applications in medicine, military, industrial, and academic fields the DWELL-IPs potential to be an inexpensive, versatile, multi-spectral, infrared detector indicates it has a bright future.