Description: We here propose the development and fabrication of an integrated sensor device capable of detecting across a wide band of UV radiation, from extreme UV (1 to 50 nm) through vacuum UV (50 to 175 nm) and into deep UV (175 to 350 nm). The proposed sensor will comprise a photodiode, a Schottky diode, and an amplifier circuit fabricated in the same process flow and monolithically integrated on the same die. We will use silicon carbide as the semiconductor material, which will make the proposed work the first time an integrated silicon carbide sensor device is fabricated. The nascent semiconductor material, silicon carbide, has found widespread application in power electronics. However, its advantageous properties as an optoelectronic detector device in the UV range (transparency to visible light and very low dark current, both results of its very wide bandgap) have not been utilized widely. With the proposed work, we therefore aim to advance the state-of-the-art in silicon carbide technology. To realize the goals of the program, which are designing and fabricating a SiC VUV detector, a SiC DUV/EUV detector, a single SiC nMOSFET, an amplifier comprised of SiC nMOSFETs, and an integrated single chip photodetector and amplifier from these individual components, we propose a work plan including process development and optimization for SiC Schottky diodes (as the VUV detector) and SiC nMOSFETs, and process optimization for SiC photodiodes (the EUV/DUV detector). We will simultaneously develop and optimize the process to fabricate all these components on the same die with the required connections to obtain a monolithic SiC detector/amplifier circuit and thereby obtain a SiC sensor-on-a-chip.

Benefits: The wideband UV detection system on a chip we plan to design and fabricate should be helpful for NASA's efforts in Astrophysics, Planetary, Earth Science and Heliophysics. We expect that the new EUV, VUV and Deep UV detection system on a chip could find applications in programs that need UV sensing. NASA Solar and Terrestrial probes, such as DYNAMIC and MEDICI, the Living with a Star program (GDC), and the Explorer Mission could benefit from the wide band technology. Ozone layer depletion is letting more UV enter the earth. The technology we are proposing here should make it easier for NASA to monitor UV penetration of the atmosphere and the effect on the earth's ecosystem. Special welding methods that are being explored MSFC Advanced Welding and Manufacturing facility could benefit from the use of the system we propose to monitor the integrity of their metallurgical results. The Lyman-Alpha Mapping Project (LAMP) on the Lunar Reconnaissance Orbiter can use our system for their lunar mapping by detecting low intensity UV from stars that reflect off the lunar surface. Furthermore, the UV emission from solar storms may be of such high energy that they may disrupt systems on the earth. The wide band UV system on a chip that we propose could be used by NASA to help monitor these storms. In addition, single chip EUV, VUV and deep UV system, with associated circuitry for readout, needs little extra components and thus can be implemented in a small payload of a spacecraft.

Military and government organizations will find our UV detectors useful in their early warning systems as rockets emit in the UV region. Furthermore, NOx compounds used in jet fuel emit in the UV spectrum when burned. This makes our devices useful for engine monitoring systems in military and commercial aircraft. UV spectrometry is a practice used throughout medicine in chemistry where our silicon carbide photodiodes can potentially replace existing diode/photomultiplier tubes in UV spectrometry systems, simultaneously reducing the cost and improving the accuracy of these systems. UV is used to study reaction kinetics in chemistry. It can also be used to distinguish between pre-cancerous growths and invasive carcinomas in head, neck, anal, cervical and breast cancer. In hospitals, UV radiation is used to decontaminate patient rooms as DNA denatures when absorbing UV light at 260 nm. The same process of using UV radiation as a germicidal agent can be used in hot tubs, aquariums, ice making machines, food processing, wineries, breweries and water purification. The wide-band gap of SiC results in leakage current that is substantially lower than silicon based devices on the market. Since our SiC photodiodes can simultaneously lower the cost and decrease the detection limit of several metals, such as lead, in AAS systems. The need for low-cost, readily available detection systems for lead is emphasized by the recent incident of Flint, Michigan