Submillimeter-Wave Schottky Diodes Integrated on Micromachined Silicon Probes

The submillimeter-wave and terahertz region (300 GHz-3000 GHz) remains one of the the most scientifically useful yet least explored regions of the electromagnetic spectrum. This spectral range is critical for many applications such as remote sensing, radio astronomy, spectroscopy and imaging. However, the measurement infrastructure for developing submillimeter-wave and terahertz devices and materials is often ill-adapted for interfacing to devices for direct in-situ characterization, too large in size, cost-prohibitive, or non-existent. In addressing this issue, the focus of this work is the integration of GaAs Schottky diodes on micromachined on-wafer probes to provide compact, low cost and innovative metrology tools for the submillimeter-wave and terahertz scientific community.

The first part of the thesis focuses on developing a robust fabrication process of heterogeneous integration of Schottky diodes onto silicon substrates. The process aims to simplify the fabrication and improve the yield. The new approach eliminates most thermal processes, including ohmic contact thermal annealing and high-temperature wafer bonding of GaAs epitaxial transfer, that can lead to wafer fracture and delamination. A 160 GHz quadrupler is implemented using the new process to assess its potential.

The second part of the thesis investigates a new approach for on-wafer calibration at submillimeter wavelengths based on GaAs Schottky diodes integrated onto silicon as an electronic standard. Comparison of the error coefficients derived for both one-port and two-port calibration applications, derived using the diode standard are shown to be in good agreement with those obtained from a conventional set of offset short and TRL standards, respectively.

Finally, two implementations of integrating GaAs Schottky diodes onto micromachined on-wafer probes metrology are described. Probes incorporating diodes for temperature sensing and s-parameters measurement are detailed and designed. The design, fabrication process and measurement plans of these integrated probes are described.