Integrated Terahertz Measurement Systems based on Heterogeneously Integrated Sensors

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

The terahertz (or submillimeter-wave) region of the electromagnetic spectrum has long been understood as crucial to fundamental scientific inquiry and progress in fields such as radio astronomy, atmospheric physics, and remote sensing. Moreover, new and emerging device concepts promise to open this largely-inaccessible spectrum to further scientific study as well as important applications in imaging, non-destructive test and evaluation, and high-bandwidth communications. Unfortunately, the infrastructure and measurement tools needed to develop these new technologies remain severely limited. Current approaches to realizing measurement instrumentation at submillimeter wavelengths are based largely on a modular approach using waveguide interfaces. This results in fully-assembled measurement apparatus with considerable geometric footprint that can prove unwieldy or unsuitable for many important scenarios, for example in situations when the device or system to test must be maintained within a shielded enclosure such as a vacuum chamber or cryostat. This project is focused on addressing this critical issue through the development of compact and low-profile measurement instruments that are based on high-performance terahertz sensors heterogeneously integrated with micromachined support membranes that allow direct-contact in situ characterization of planar devices and systems at terahertz frequencies. As a consequence, this work will have broad impact on the growing terahertz research community through the availability of new and advanced metrological instrumentation that permit measurements that presently are not possible or feasible. The creation of new measurement techniques and capabilities is fundamental to the advancement of science; scientific discovery and progress in engineering are predicated on the creation of instruments that open new physical domains for experimentation and inquiry. This work represents an initial, critical, and necessary step towards developing instruments that overcome the inherent drawbacks limiting current approaches to terahertz metrology. The goal and scope of this project is to advance the infrastructure for measurement and characterization of terahertz devices, components, and systems through the development of instrumentation technologies that are based on heterogeneous integration. The research pursued focuses on heterogeneous integration across materials systems (e.g., III-V semiconductors and silicon) and across physical domains (e.g., electronics and mechanics). Towards this end, the specific approach to be undertaken includes three primary thrusts: (1) development of processing technologies for low-parasitic terahertz Schottky diode sensors heterogeneously integrated onto thin silicon membranes, (2) investigation and implementation of silicon membrane-based micromachined on-wafer probes incorporating integrated Schottky sensors, and (3) research and prototyping of compact, high-order terahertz frequency multiplier sources for integration with test and measurement instrumentation based on heterogeneous integration. There is inherent intellectual merit in researching processes that enable such integration and a significant effort of this proposal is dedicated to investigating methods that permit fabrication of high-performance terahertz electronic sensors with mechanically-robust host substrates amenable to direct, physical contact interfaces without need for fixturing. Fundamental issues of terahertz device design, fabrication technology, and metrology will be addressed during this work with the aim of realizing new and advanced instrumentation that permit measurements that presently are not possible or feasible.