MSE Seminar: Ashutosh Kumar

PhD Candidate advised by Dr. Wolfgang Windl, Department of Materials Science and Engineering, The Ohio State University

Abstract

Advancement of nuclear power technology has led to the critical questions of detecting emission of harmful radiation and monitoring the exact amount of fissile material present. Thus, finding devices that allow precise detection and monitoring in even the harshest nuclear environment has become one of the key challenges in nuclear energy technology. The detector materials and device structure need to allow fast and accurate measurements at high temperatures as well as survive significant radiation and corrosive environments. While semiconductor based devices fulfill the measurement requirements, current materials (predominantly silicon) are prone to radiation damage and seize functioning at approximately 150 °C. Among alternative materials, silicon carbide (SiC) has been suggested to potentially overcome these deficiencies. In this project, we develop a SiC based detector, demonstrate its function, and develop computational modeling that can predict the long-term performance of the detectors in harsh nuclear environments. For this project, we target the extreme conditions found in pyroprocessing (nuclear fuel dissolved in molten salt at processing temperatures of 500 °C or higher), a method to reprocess spent nuclear fuel with potential importance for next-generation power plants. While especially the high temperatures limit many design choices for the device structure, we show that a Schottky diode made with 4H-SiC and nickel-based Schottky and Ohmic contacts indeed works at temperatures up to at least 500 °C. In order to computationally simulate temperature and irradiation effects, we have developed a novel multiscale modeling methodology consisting of continuum-level simulation of irradiation damage and its evolution as a function of temperature and quantum-mechanical modeling of the effect of damage on the electrical properties of 4H-SiC. In addition, device modeling has been developed to predict the detector operation as a function of environmental conditions, which has been used for calibrating the charge measured in the detector versus impacting α-particle energy and to deliver a proof-of-concept for operation in the pyroprocessing environment.

Bio

Ashutosh completed his Bachelors (B. Tech) degree in Metallurgical and Materials Engineering (MME) from Indian Institute of Technology, Roorkee (IIT-Roorkee), India, in 2009. At IIT, he was awarded the Institute Silver Medal for scoring the highest GPA in the 2005-2009 MME batch, and also the Best Undergraduate Project Medal. He joined OSU in the fall term of 2009 as a graduate student in the MSE department. As a member of Prof. Windl’s research group, he has been studying, both theoretically and experimentally, the potential of silicon carbide as a material for radiation detector devices. This work has been done in collaboration with Prof. Blue in the Nuclear Engineering department at OSU. As a part of this project, he also spent 5 weeks during the summer of 2012 at Fraunhofer Institute of Integrated Systems and Device Technology, Erlangen, where he collaborated with Prof. Peter Pichler. In his spare time, he likes to do photography or write Hindi poems.