Tailoring and characterizing the quantum efficiency of semiconductor photodetectors

In this thesis, we develop and utilize a combination of analytical and computational approaches for the modeling, analysis and characterization of the spectral behavior of quantum efficiency for the development of advanced semiconductor photodetectors. This research focuses on two specific photodetector designs based on the resonant cavity enhanced (RCE) detection scheme. The quantum efficiency of the first device approaches the ultimate limit of unit quantum efficiency. The second device is designed to reduce the acute wavelength selectivity inherent in resonant enhancement. Both detectors possess wide electrical bandwidth making them suitable for applications ranging from quantum optical experiments to telecommunications.; To ascertain how closely design goals have been achieved, we characterized the quantum efficiency of the fabricated RCE detectors by conventional radiometric techniques. These were implemented with utmost care for accuracy especially in the measurement of the near-unity efficiency devices. We also set up instrumentation to test the electrical high-speed response required in applications where optical stimuli vary rapidly in time.; The main caveat of conventional measurement of quantum efficiency is the reliance on traceable radiometric standards. As an alternative, we investigate the incorporation of entangled photon fields in a novel and absolute method which does not rely on measurements relative to standardized light sources. In this technique, two photon streams with the same flux are generated in a nonlinear crystal by parametric-down conversion. The efficiency of any one of the detectors placed in the path of two photon streams can, in principle, be deduced by correlating their photocurrent whereby one stream serves effectively as reference for the other. We applied this technique to characterize the quantum efficiency of commercial single-photon counting (digital) avalanche photodiodes. We explore the potential applicability of the absolute calibration to photocurrent-mode (analog) detectors. This is especially challenging because analog photodetectors can not distinguish individual photons and the entangled photon streams are very weak compared to the sensitivity of typical analog detectors.