Silicon electronics face a technological bottleneck even as there is a need for devices that operate at ever increasing speeds. Terahertz (THz) technology is viewed as a potential solution to this problem as it will enable devices that operate at speeds of 100 GHz to 10,000 GHz, far faster than conventional electronics. The project will create active THz devices using a relatively new family of semiconductors, organic-inorganic hybrid lead halide perovskites. Perovskites have recently gained significant attention because of their potential for high-performance solar cells. The basic properties of perovskites that make them attractive for solar cells also make them appealing for THz applications. For example, the response of perovskites to light can be altered chemically by changing the halide group in the molecule. Perovskites are also easy to process. High quality thin films of perovskites can be readily deposited via a simple spin coating process that is routinely used in the semiconductor processing industry. Different perovskites with distinct optical and electronic properties can be easily deposited next to one another. In contrast, this is difficult to do with conventional inorganic semiconductors, such as silicon and gallium arsenide. This ease of fabrication allows for new device capabilities that are simply not possible when only one type of semiconductor is used. The PI will work to broaden participation in science education through experiences such as the Utah Science Olympiad. The PI will develop classes for high school teachers, involve undergraduate and high school students in research, and engage with first generation students in the Salt Lake Valley.
The proposed work intends to develop a new class of terahertz (THz) devices based on organic-inorganic lead halide perovskites. These semiconductors, while well examined for photovoltaic applications, have been almost completely unexplored for THz applications. They are extremely attractive for THz applications because their optical properties can be chemically engineered with relative ease. Since they can be solution processed, multiple perovskites can be cast and delineated with extremely high precision in close proximity to one another, without any degradation to the material response. We intend to develop a unique fabrication technique that allows for patterning of these semiconductors with um-scale precision using a polymer delamination process that protects the deposited perovskite layers, while additional layers are deposited and defined. By doing so, we expect to create active THz devices that exhibit functionality that is not possible using only a single semiconductor, such as silicon or gallium arsenide. Specifically, we intend to demonstrate (i) ultrafast THz frequency agile devices, (ii) electro-optic devices using 2D perovskites, where the applied (THz) electric field can induce the Stark effect or quantum confined Stark effect in the multiple quantum well structures, and (iii) field effect transistors based that exhibit optical wavelength sensitive control of the THz properties. The proposed research offers transformative capabilities because the use of multiple perovskites within a single device proposed here is technically challenging to achieve using conventional semiconductors.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
