Date of Award

August 2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Prasenjit Guptasarma

Committee Members

Yi Hu, Chanyeop Park, Benjamin Church, Hamid Seifoddini

Keywords

Cd3As2, IR- light sensing, Photo-thermo-voltaic Effect, Photodetectors, Seebeck Effect, Thermal conductivity

Abstract

By harnessing the extraordinary properties of quantum materials, researchers are not just conducting experiments but shaping the future of technology. Quantum materials enable the development of smaller, faster, and more efficient electronic components, potentially surpassing the physical limits of silicon-based devices. This dissertation will delve into quantum materials' electrical, optical, and thermal characteristics, specifically focusing on cadmium arsenide (Cd3As2) crystalline platelets. This topological semimetal, which is a three-dimensional analog of graphene, has potential in applications such as infrared light detection and thermoelectricity. The study also explores the possible uses of a heterojunction formed by combining bismuth selenide (Bi2Se3), a topological insulator, with tin telluride (SnTe), a topological crystalline insulator.In this study, we developed a high-bandwidth, self-powered infrared photodetector based on the optically induced Seebeck effect in Cd3As2, which operates at room temperature. The photocurrent was detected at a modulation frequency of 6 kHz, and the intrinsic bandwidth is expected to reach the terahertz range. The sensor exhibits a responsivity of 0.27 mA/W at room temperature, comparable to the reported value for a graphene-based infrared photodetector. Our results suggest that Cd3As2 is a promising candidate for fast response and high bandwidth applications. Unlike conventional photodetectors made from materials such as silicon, which are limited by their bandgap of 1.1 eV, Cd3As2 offers spectrally broad applications in optoelectronics. We also measured the thermal conductivity of crystalline Cd3As2 platelets and studied their temperature dependency from 180 to 300K. Understanding Cd3As2's thermal properties at these temperatures is essential for optimizing its use in thermoelectric generators (TEGs), which convert waste heat from industrial processes, automotive engines, and power plants into electrical energy. Improving the efficiency of Cd3As2-based TEGs can significantly contribute to energy conservation and sustainability across various sectors. Moreover, we have addressed the limitations and challenges associated with doping Cd3As2 with copper and creating a heterojunction of Bi2Se3 and SnTe. Copper doping in Cd3As2 is expected to enhance its electrical conductivity by introducing a bandgap of approximately 0.3 eV, making it more suitable for optoelectronic devices with improved response time and efficiency. These improvements are critical for applications in high-speed photodetectors, infrared sensors, and other optoelectronic components where rapid response and high sensitivity are essential. Forming a heterojunction between Bi2Se3 and SnTe offers significant advantages for infrared photodetection. Heterojunctions between topological insulators and other materials can create unique electronic interfaces that enhance light absorption and carrier separation, thereby improving photodetection capabilities.

Download

Share

COinS