Wide bangap GaN-based heterostructure devices are capable of delivering superior performance under extreme operating conditions including high voltage, high-temperature, high-frequency, high-power and chemically and mechanically harsh environment. Such a capability can be attributed to the intrinsic material properties including high electric breakdown field, high electron saturation velocity, low intrinsic carrier concentration, strong charge polarization, and strong chemical inertness. GaN electronic devices are emerging as the promising candidates for next-generation wireless power amplifiers, high-efficiency power converters and high-temperature sensors (e.g. gas, pressure sensors). This work focuses on the development of GaN device technologies for exploration of novel sensing and...[ Read more ]

Wide bangap GaN-based heterostructure devices are capable of delivering superior performance under extreme operating conditions including high voltage, high-temperature, high-frequency, high-power and chemically and mechanically harsh environment. Such a capability can be attributed to the intrinsic material properties including high electric breakdown field, high electron saturation velocity, low intrinsic carrier concentration, strong charge polarization, and strong chemical inertness. GaN electronic devices are emerging as the promising candidates for next-generation wireless power amplifiers, high-efficiency power converters and high-temperature sensors (e.g. gas, pressure sensors). This work focuses on the development of GaN device technologies for exploration of novel sensing and control ICs. The technologies developed in this work promise not only to deliver integrated sensors, but also provide on-chip sensing and control circuits that are promised to deliver optimized performance, increased functionality and enhanced reliability to the key functional blocks that operate under extreme conditions.

Two integration technologies of surface acoustic wave (SAW) devices with HEMT (high electron mobility transistor) on AlGaN/GaN heterostructure are proposed. The first one is a planar process with isolation achieved by fluorine plasma implantation. This approach not only is preferred in high-frequency SAW/HEMT circuits because of the smooth surface, but also eliminates the need of dry etching process which inevitably induces crystal damages. The second one is a novel SAW device featuring invisible (or transparent) 2DEG interdigitated transducers (IDTs) instead of metallic IDTs. Thus the active sensing area can be placed on top of the 2DEG IDTs rather than along the propagation path in the conventional SAW devices.

A HEMT-compatible lateral-field effect rectifier (L-FER) with low turn-on voltage, low on-resistance, and high reverse breakdown is used for zero-bias RF mixer that features no dc bias, zero dc power consumption, low conversion loss, excellent linearity and high power handling capability. In addition, the good circuit performance has been achieved up to 250 ℃, exhibiting its usefulness in high-temperature wireless sensors that are finding increasing demand in industrial control, automotive and aviation systems, and petroleum exploration. Detailed temperature dependences of the L-FER are characterized and analyzed with an equivalent circuit model.

An integration platform for GaN smart power chip technology is proposed. Fully integrated voltage reference generator and temperature-compensated comparator circuits are demonstrated with excellent stability in wide range of operating temperature (up to 250 ℃) and low power consumption --- a performance that exceeds the capability of Si CMOS technologies.