Epitaxial Quantum Dot Infrared Photodetectors

Abstract

The article focuses on quantum dot‐based infrared photodetectors. Self‐assembled quantum dots, dot in the well structures, and quantum ring structures are discussed for various wavelength ranges and operating temperatures. Calculations of the energy states in dot structures and the effect of the dot sizes are briefly described. Dark current and detectivity and effect of different parameters on the performance are also described. Extension of the response region to terahertz using quantum dot‐based devices is also discussed. Present performance of the quantum dot devices with possible improvements is provided while summarizing the status of quantum dot‐based focal plane arrays.

Quantum-Dot Single-Electron Transistors as Thermoelectric Quantum Detectors at Terahertz Frequencies

“…20 Quantum-dot infrared photodetectors (QDIPs) represent a promising route to overcome some of the major limitations of terahertz QWIPs. 21 In particular, the energy level configuration and the orbital occupation can be controlled via the QD diameter−height and the gate bias, respectively. QDs are also inherently sensitive to normal incidence photoexcitation and, therefore, do not require 45°polished facets, metal gratings, 22 engineered band mixing, 22,23 or reflectors, as conventionally needed for QWIPs.…”

“…This effect is then expected to give rise to a more efficient detection, as a consequence of a larger quantum efficiency and to enable operation at higher temperatures (up to 50−60 K). 21,23 The reduced dependence of the density of states upon the temperature and the longer carrier lifetime (1−2 orders of magnitude) in QDs have the additional advantage of reducing the dark current with respect to QWIPs. 26 QDIPs are promising candidates for applications in terahertz communication.…”

“…Quantum-dot infrared photodetectors (QDIPs) represent a promising route to overcome some of the major limitations of terahertz QWIPs . In particular, the energy level configuration and the orbital occupation can be controlled via the QD diameter–height and the gate bias, respectively.…”

“…Most importantly, the three-dimensional confinement leads to the phonon bottleneck effect, inhibiting phonon scattering in QDs compared to QWs , and increasing the lifetime of photoexcited carriers (∼5–10 ps), whose phonon-mediated relaxation to the ground state is eventually hindered in favor of an enhanced probability of tunneling out of the dot. This effect is then expected to give rise to a more efficient detection, as a consequence of a larger quantum efficiency and to enable operation at higher temperatures (up to 50–60 K). , The reduced dependence of the density of states upon the temperature and the longer carrier lifetime (1–2 orders of magnitude) in QDs have the additional advantage of reducing the dark current with respect to QWIPs …”