Thesis (Ph. D.)--University of Rochester. The Institute of Optics, 2020.
Detectors in the mid-wave infrared region are designed to limit the amount of noise current produced, as this is often the limiting mechanism. III-V based systems are one approach to creating such detectors, as designs are flexible. However, they are still limited by dark currents, produced by thermal excitations within the material, leading to an increase in noise and a decrease in quantum efficiency. The resonant cavity design will limit the wavelength sensitivity, thereby enabling a decrease in background current noise. The aim of the resonant cavity structure is to decrease the dark current noise source by reducing the amount of material needed to detect the signal light while confining the light in such a way as to keep the quantum efficiency high, enabling an increase in performance of III-V detectors.
The goal of this thesis is to examine the effect of design parameters such as mirror types and cavity construction on the performance of these resonant cavity devices. Specific detectivity and quantum efficiency are of specific importance, but notes are made to spectral response and operating parameters (such as angle of incidence and temperature). Models of these structures have been shown to agree well with measurement and are adaptable to other materials. Mirror composition plays a major role in light confinement for absorption. The construction of cavities with a spectral response bandwidth of less than 100 nm is shown. Careful cavity construction has been shown to permit thin contact regions without much degradation of performance. Device results are presented for the various combinations of materials and conditions. A 35 times decrease in dark current over its usual thicker design was measured for an InAs based resonant cavity device. Angle and thermal tuning of these devices is also examined with models and measurements, to enable their further use. Tolerancing of the devices is examined for future reference.
