Fast photo-detectors with high quantum efficiency in the UV spectral region
Abstract
This project seeks to identify materials and schemes that can surpass the present limitations of detection technologies by exploring novel methodologies and phenomenologies which may improve how neutrons or gamma rays are sensed and recognized from radiological and nuclear materials of interest. Current radiation detection technologies suffer from setbacks generated by making tradeoffs for many desired features. Such tradeoffs are particularly evident in the light collection stage of scintillation detectors. Photomultiplier tubes (PMTs) for light collection, have remained the gold standard even though they are non-robust, have large associated monetary and power expenses, experience long response times, and may have relatively poor quantum efficiency (QE ? 25%). Understanding the phenomenology governing novel materials may expose new insights available for radiation-sensing materials and methodologies that offer greatest benefit. It is expected to identify such neutron-sensing materials satisfying the following characteristics: fast response times, non-toxicity, low noise and high quantum efficiencies in the wavelength region that is typical of current scintillators (near blue to deep ultraviolet). Thus, this project revolves around the development of novel, robust, ultra-fast, low-power and cost-effective photo-detectors with high quantum efficiency in the wavelength region near blue to deep ultraviolet of interest for C-WMD nuclear radiation detection using typical scintillators. The proposed approach is based on Mott insulators - i.e. materials that exhibit insulator/metal transitions under adequate stimuli- and Plasmonic approaches to enhance light absorption and hence ultimate sensitivity. Thus, it is proposed to exploit metal-insulator transitions (MIT) in a Mott material, which can lead to very fast, very sensitive and cost-effective radiation detection which will thus contribute to C-WMD needs to detect potential nuclear threats. In particular it is proposed to work with the insulator-metal transition (IMT) of vanadium dioxide (VO2) thin films, since it occurs at temperature close to ambient, and leads to quite significant changes in the optical and electrical properties of such material, leading to strongly detectable parameters and therefore suitable for this application. In order to enable UV detection, it is proposed to combine this materials with doped titanium dioxide (TiO2:doped), which is a strong UV absorber that when adequately doped can render VO2 metallic via photocarrier excitation.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 13, 2016
- Source ID
- HDTRA11610056
Entities
People
- Rosa Lukaszew
Organizations
- College of William & Mary
- Defense Threat Reduction Agency