Electronic Sensing: Infrared Detection using Intraband Transitions of Colloidal Quantum Dots
Abstract
The research program is to investigate the intraband transition of n-doped colloidal quantum dots as a new approach to fabricate solution processable mid-infrared optical materials and detectors. In the intraband scheme, we will use the infrared transition between the confined states within the conduction or valence band. The advantage of the intraband scheme is that the transition energy can be fully tunable across the mid-infrared by making quantum dots of sizes in the 3-10 nm range, depending on one of the carrierÕs effective mass, but irrespective of the interband gap. Compared to the interband route which requires to start from very small gap semiconductors, the intraband transition affords a greater choice of materials since wide band gap semiconductor can a priori be used. However, to access the infrared transition, the dots need to doped, and this proposal focuses on n-type quantum dots. This work will therefore start with investigating photodetection using the intraband transitions of n-doped HgS and HgSe colloidal quantum dots, which are the two systems for which we previously demonstrated intraband photocurrent spectra. Using these model systems, we will explore the advantages and disadvantages of the intraband approach and contrast to intraband detection. Our particular emphasis will be on the aspects of the optical absorption strength, the linewidth of the absorption, the sensitivity to doping and the specific effects of size disorder on the intraband scheme. To make other n-type quantum dot materials with good environmental stability, we will focus on materials with a known low energy conduction band. By developing novel synthesis schemes, we will explore wide gap n-doped oxides as well as others n-doped chalcogenides. The motivation for this basic study is to demonstrate that the intraband approach gives access to new infrared detection materials, which might provide advantages such as lower toxicity or transparency in the visible. This experimental research program will include the synthesis of colloidal nanomaterials, the fabrication of thin films, the measurement of transport properties using field-effect transistors, and the fabrication of single element photodetectors with their fully characterized performances in the mid-infrared.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 19, 2019
- Source ID
- W911NF1810207
Entities
People
- Philippe Guyot-Sionnest
Organizations
- Army Contracting Command
- United States Army
- University of Chicago