Ph.D Thesis

Ph.D StudentSvetlitza Alexander
SubjectCMOS-SOI-NEMS Thermal Antennas for Uncooled Passive
Imaging in THZ Range
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROFESSOR EMERITUS Yael Nemirovsky


Despite great scientific interest since at least the 1920s, the THz frequency range remains on of least tapped regions of the electromagnetic spectrum. Sandwitched between millimeter-wave and optical technologies, its commercial uses are only starting to emerge. In particular, THz imaging can find useful medical and security applications as THz radiation is both penetrating and safe.

Sensing pixels based on thermal antennas allow uncooled passive THz imaging. Thermal antennas made of a resistive layer directly absorb the THz waves and convert them into heat. When positioned in a focal-plane array and backed by a perfect reflector at λ/4 distance, the antennas form a band-stop Frequency Selective Surface. The temperature increase is detected by a thermal sensor - a suspended transistor in a diode-like connection. Thermal antennas are implemented in cost-effective CMOS-SOI-NEMS technology. The focal plane array is first fabricated in a standard CMOS-SOI process. By applying NEMS post-processing using the CMOS metallization layers as built-in masks, nano-machined suspended directly-absorbing resistive antennas integrated with thermal sensors are obtained, thus achieving good thermal isolation as well as low thermal mass.