Silicon based terahertz emission and detection devices
Recently, there have been significant advances in materials diagnostics by the terahertz frequencies, as higher power sources and more sensitive detectors open up a range of potential uses. Applications have been demonstrated in many fields, including semiconductor and high-temperature superconductor characterization, tomographic imaging, label-free genetic analysis, cellular level imaging and chemical and biological sensing. All these have thrust terahertz research from relative obscurity into the limelight.
The techniques to generate terahertz radiation in the above-mentioned applications were dominated by optical techniques. Compact semiconductor sources and detectors, however, have remained largely underdeveloped. In this dissertation, I will describe a novel approach to realize compact semiconductor sources: electrically pumped impurity doped silicon terahertz emitters based on shallow impurity intracenter transitions. The fabrication and characterizations of electrically pumped terahertz emitters will be outlined. The device performance of donor- and acceptor-doped silicon terahertz emitters will be compared, and the requirements to realize terahertz lasing will be analyzed. I will also discuss the effects of externally applied stress on terahertz emission as a potential way to achieve tunability.
Two types of terahertz detectors will be discussed in this dissertation, impurity doped silicon devices and silicon germanium multiple quantum well devices. The device design, fabrication and characterization will be outlined.
Our results suggest that it would be possible to realize compact terahertz emitters and detectors from silicon based materials. These results may open new horizons in device design and applications in the THz range of the electromagnetic spectrum.