Modulating Infrared Optical Response in CdO by Transport Properties and Heterostructure Design
Open Access
- Author:
- Cleri, Angela
- Graduate Program:
- Materials Science and Engineering (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 01, 2023
- Committee Members:
- John Mauro, Program Head/Chair
Susan Trolier-McKinstry, Major Field Member
Jon-Paul Maria, Chair & Dissertation Advisor
Noel Giebink, Outside Unit & Field Member
Joshua Caldwell, Special Member
Joshua Robinson, Major Field Member - Keywords:
- plasmonics
cadmium oxide
infrared
optics
materials
transport properties
sputtering
thin film
defect chemistry
plasmon polariton
transparent conducting oxide
nanophotonics
hyperbolic
ion irradiation
high-power impulse magnetron sputtering
HiPIMS
physical vapor deposition
PVD
doping
metamaterials - Abstract:
- Electronic circuits have dominated devices for decades, allowing fine control of electron transport and storage. However, electrons’ tendency for scattering restricts the efficiency of these devices in carrying digital information from one point to another. For instance, modern microprocessors employ higher counts of ultrafast transistors, but the delay associated with copper wire interconnects needed to transmit digital information hinders the speed of these circuits. Due to their massless nature, electromagnetic waves (or light waves) scatter less frequently, and travel much faster, than electrons. Thus, they are much more effective at transmitting data from one point to another, motivating the development of photonic circuits. Currently, the major drawback for optical interconnects, such as optical fibers, is the bulky components relative to electronic circuits due to the diffraction limit; optical fiber widths must exceed half the light’s wavelength to avoid interference between closely spaced waves. Electronic circuits are routinely fabricated with nanometer scale components, but optical circuits can only be fabricated on the micrometer scale. While fiber optic cables can transmit data with a capacity >1000 times that of electronic interconnects, they are ~1000 times larger in size. Manipulation of plasmons, or free electron oscillations in a metal coupling to the electric field of light, enables sub-diffractional light-matter interactions which could be the necessary bridge between electronic and photonic circuits. While plasmonics research has traditionally focused on the UV-visible spectral range, there is much promise for hosting plasmonic resonances in the infrared (IR). In addition to photonic circuits, plasmonics has powerful implications for IR detection technologies such as thermal imaging at long distances, chemical composition analysis, and imaging in the presence of obscurants. Cadmium oxide (CdO) has been identified as an excellent IR plasmonic material, as its tunable carrier concentration enables Drude metal behavior across the mid-IR, and its high mobility allows resonances with low loss and narrow frequency bands. Further studying the relationship between transport properties and optical properties in CdO is a necessary step in developing IR plasmonic devices with spectrally broad and potentially spatial tunability. This dissertation demonstrates fabrication techniques to engineer CdO optical properties in all three spatial dimensions. Using high-power impulse magnetron sputtering, donor doped films exhibit record-breaking magneto-optic enhancement in the infrared and demonstrate exceptionally low-loss hyperbolic plasmon polaritons which will be imaged in real-space for the first time. Further, ion irradiation and ion implantation are used to locally induce both native and extrinsic defects and extend light manipulation principles to the in-plane dimensions.