NSF Award
0943788
This Small Business Innovation Research (SBIR) Phase I project will assess new designs for single-element solid state ultraviolet (UV) detectors based on BeZnO alloy material with cut-off wavelengths 300 to 370 nm, thereby eliminating undesired visible and infrared (IR) radiation. Photomultiplier tubes (PMTs) and silicon photodiodes can be used for selective UV detection in this region. PMTs are bulky and require high bias voltages (ca. 1000 V), and both PMTs and silicon possess a broad spectral response. System quantum efficiencies, near 30%, are reduced by filtering. Wide band gap BeZnO semiconductor materials can now be grown with optical cutoff wavelengths in the desired UV range. The research objectives are to develop a new class of high-sensitivity UV detectors featuring high-speed response, compactness, lightness, low operational voltage, low noise current, high quantum efficiency, high visible/IR rejection, and high radiation hardness. The crystallinity, electrical, and optical properties of BeZnO will be characterized and theoretical simulations performed to optimize layer sequences and doping profiles for metal-semiconductor-metal (MSM) UV detectors. Anticipated technical results are 300 to 370 nm cutoff wavelength, greater or equal than 5 orders of magnitude UV to Visible/IR responsivity, 60% QE, and 0.1 to 1 microsec response time. <br/><br/><br/>The broader impact/commercial potential of this project will be enhancement of scientific and technological understanding of the crystalline qualities of BeZnO semiconductor materials and how crystalline defects impact optical responsivity in the ultraviolet (UV) and in the visible and infrared (IR) spectral regions. Relating defect types and densities to optical response is of interest in photodetector development. Detection of UV in the presence of large visible/IR backgrounds has many commercial and military applications. Commercial applications include flame and heat sensors, medical sterilization monitoring, plasma diagnostics, Earth monitoring from look-down space platforms, sniper location by law enforcement, early stage sparking failure in high voltage transmission lines/transformers, and combustion engine monitoring. UV detectors can be used to determine if a flame is associated with a hot object, an important consideration in fire detection systems. Military applications include the detection of missile/gun plumes, missile guidance, base perimeter monitoring and detection of enemy combatants, and detection of biological/chemical agents for defense and homeland security. The technology can be further developed such that light-weight, high-resolution, and high-speed 1-D and 2-D imaging systems can be deployed. The technology area is semiconductor-based optical sensors, and the market sector is UV radiation monitoring.
