EAGER: Flexible III-N High-Electron-Mobility Transistors with Controlled External Bending Strains for Wide-Bandgap Semiconductor Devices

University Of Houston, Houston TX

Investigators

Abstract

Group III-Nitride (III-N) semiconductors have brought significant benefits to mankind as energy-efficient and environment-friendly light sources, as recognized by the Nobel Prize in Physics 2014. They are also important materials for energy-efficient electric power conversion and switching, wireless communication, electronic warfare, and optical storage systems. This project proposes to study the expanded functionality and further enhanced performance of the already high-performance and high-efficiency devices using mechanical bendability of the device structure. This project is expected to produce new-concept devices and related new device physics for the advancement of knowledge in the device technology. Furthermore, the outcome of this research will provide a potentially disruptive semiconductor platform that can be integrated in other semiconductor devices with multi-functionality and application versatility for energy saving and harvesting. The new concept has been developed based on theoretical studies and has yet to be proven by the demonstration of working devices, which is one of major objectives of the proposed project. The societal and economic impacts will be significant because electronics, photonics, and energy systems based on semiconductors are the backbone of modern technology and will be even more critical in the future with the adoption of electric vehicles and smart-grid systems. As an example, 30% of electrical energy passes through power electronics converters and 22% of total generated electricity is consumed in lighting, which means that significant benefits are expected in energy saving and reduction of greenhouse-gas emission. Education and outreach programs integrated with the research program will contribute to the dissemination of knowledge on green energy systems, semiconductor devices for sustainable technology, and their societal and environmental impacts. Flexible devices based on III-N heterostructures can be equipped with new functionalities and even further improved performance characteristics compared to wafer-based non-flexible devices by exploiting their unique properties of spontaneous and piezoelectric polarizations. Therefore, they open an opportunity to new-concept devices, multi-functional mechano-electro-photonic (MEP) devices, beyond just mechanically flexible devices, by the active control of the polarizations with variable external strains. The goals of the project are to prove the concept of the active polarization engineering applied in flexible III-N structures and to lay the foundation for the MEP devices in electronic, photonic, and energy-harvesting applications. Various multi-functional and/or higher-performance MEP devices based on III-N semiconductors will be developed by utilizing the interactions between electronic and optical properties and mechanical forces in the flexible heterostructures. The changes in fundamental characteristics of flexible high-electron-mobility transistors with controlled bending strains will be investigated via both modeling and experimental studies to prove the proposed concept of active polarization engineering. Technical methods and tasks include (1) device simulation with various curvature radii, (2) the development of high-fidelity fabrication process for bendable devices, and (3) the development of a physical model for the operation of MEP devices. This project is to produce proof-of-concept actively polarization-engineered electronic devices and related new device physics to demonstrate the potential of a new technology platform. The MEP devices offer the potential to radically change the understanding and applications of III-N semiconductor devices, leading to the creation of new-type devices and systems. New device physics and modeling results including the effect of static and dynamic external strains will provide a theoretical background of such devices for various applications 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.