Characterization and Development of Submillimeter Wavelength Devices Incorporating Vanadium Dioxide Thin Films

Abstract

Vanadium dioxide exhibits an insulator-to-metal transition (IMT) accompanied by a decrease in resistivity of several magnitudes and a large increase in reflectivity. The IMT can be triggered in multiple ways. The most common method is to heat a sample above 67°C causing it to go from a semiconducting to metallic phase. However, the transition can also be triggered using current injection, a change in electric field, or an optical pump. A diverse array of potential applications exploiting VO 2 including next generation CMOS, switches, thermal relays, intelligent window coatings, bolometers, filters, memory and logic devices, and reconfigurable circuit elements and antennas from dc to x-ray wavelengths have been proposed in the literature. I would like to thank my advisor, Bobby Weikle, for all of his assistance, teachings, guidance, and encouragement on this journey. I give thanks to my committee members, Prof. Art Lichtenberger, Jiwei Li, Mircea Stan, and Jim Fitz-gerald for their insight and advice along with Prof. Stu Wolf for sharing his ideas and guidance. Thank you Salinporn (Lin) Kittiwatanakul for providing the VO 2 film and helping with the materials science diagnostics, Matt Bauwens for his help with the on-wafer terahertz measurements, and Lei Liu for getting me started on my own research while he was finishing his PhD. Acknowledgement also goes to all my group mates, past and present, in the FIR lab for their valuable discussions and assistance throughout my research and those in UVML who taught me and assisted me with the processes and procedures necessary used in this research. I extend my gratitude to the FIR lab manager, Dr. Acar Isin, for his help with the experimental setups and earlier on with cryogenics and to those who work in UVML,

Dynamically Reconfigurable Microwave Circuits Leveraging Abrupt Phase-Change Material

“…Typical cleanroom processes, when performed for extended periods of time, seem to affect the quality (stoichiometry), thickness, and conductivity of VO 2 [19]. The potentially detrimental processes utilized on the sample presented in this paper include cleaning with RF oxygen plasma, rinses with photoresist removal agents and de-ionized water, and heating (max.…”

“…110 • C). However, the processing time required for this sample was very brief: seconds or minutes instead of the hours taken in the investigation in [19]. Additionally, the film's DC conductivity in the ON and OFF state was measured before and after sample fabrication using a van der Pauw method.…”

Terahertz coded aperture mask using vanadium dioxide bowtie antenna array

“…The change in resistivity varies from about one-half order of magnitude to five orders of magnitude depending on the transition method and film parameters [7]. A change in transmission of more than 40% is reported between the semiconducting and metallic state at terahertz, infrared, and optical frequencies [4][5][6][7]. These properties make VO 2 attractive for a terahertz switch capable of modulating a signal beam.…”

“…The array is found to be capable of modulating the transmission of a 500 to 750 GHz signal by up to 28 dB. A 100 nm thick VO 2 film located at the antenna feed point modulates the reflectance of the bowtie antenna such that it reflects the submillimeter wave signal when the VO 2 is in the off state (semiconducting) and transmits the signal when it is in the on state (metallic) [4]. A WR-1.5 one-port measurement system was assembled to validate the model of the bowtie antenna array.…”