InGaAs Nanowire and Quantum Well Devices

To fulfill the increasing demand for high-speed electronics used for computation or communication is one everlasting challenge for the semiconductor industry. Emerging fields such as quantum computation also has a need for circuits operating at cryogenic temperatures. The metal-oxide-semiconductor field-effect transistor (MOSFET) is the main component in modern electronics, traditionally fabricated in Si. However, III-V materials generally exhibits higher electron mobility compared to Si. This enables the realization of MOSFETs with higher operational speed or lower power consumption. While a nanowire geometry, where the channel is gated from multiple sides brings an increase in the electrostatic gate control, allowing for further gate length scaling. In this thesis, lateral InGaAs nanowire and quantum well devices have been fabricated and characterized with the purpose of understanding the electron transport and its limitations over a wide temperature range. MOSFETs at cryogenic temperatures, where the phonon occupation is low, are highly sensitive to disorder and defects in the semiconductor/oxide interface. InGaAs RF MOSFETs with different spacer technologies for reducing capacitances have also been fabricated and characterized. Optimizing the spacers for low capacitance and low access resistance is a key design consideration when fabricating devices for high-frequency operation.