Suspended aluminum gallium nitride/gallium nitride-on-silicon microstructures for high-temperature-tolerant micro-electromechanical systems
- In this Ph.D. work, advances have been made in the development of AlGaN/GaN-on-Si as a material system for high-temperature-tolerant micro electromechanical systems (MEMS). Firstly, a unique micro-fabrication process for making fully-suspended MEMS devices from AlGaN/GaN-on-Si wafers has been developed. In addition, electrical and micro-structural behaviors of Ti/Al/Pt/Au Ohmic metallization for AlGaN/GaN devices at high temperatures in air has been studied for the first time in literature. It has been shown that the contact resistance of the Ti/Al/Pt/Au Ohmic metallization remained very stable (< 3% variations) at 600°C in air for 10 hours after the initial "burn-in". Moreover, the degradation phenomena and mechanisms of the two-dimensional electron gas (2DEG) in the AlGaN/GaN heterostructures at 600°C in both oxidizing and inert ambient conditions have been examined. It has been discovered that oxygen plays a critical role in suppressing the strain relaxation of the AlGaN layer. Furthermore, suspended AlGaN/GaN MEMS ultraviolet (UV) photodetectors with in-situ heating capability have been designed, micro-fabricated and tested. The in-situ heating is used to overcome the chronic problem suffered by GaN-based optical detectors -- long decay transients (hours to days) of the photocurrent after the UV illumination source has been removed. The decay times of AlGaN/GaN UV photodetectors have been reduced from ~39 hours to ~24 seconds using the suspended AlGaN/GaN device architecture. The results demonstrate that AlGaN/GaN-on-Si, when interfaced with appropriate metallization and dielectrics, is a promising material platform for manufacturing high-temperature-tolerant MEMS.
|Type of resource
|electronic; electronic resource; remote
|1 online resource.
|Stanford University, Department of Electrical Engineering
|Howe, Roger Thomas
|Howe, Roger Thomas
|Statement of responsibility
|Submitted to the Department of Electrical Engineering.
|Thesis (Ph.D.)--Stanford University, 2017.
- © 2017 by Minmin Hou
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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