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Above: A carbon nanotube vacuum microelectronic device operated at high temperature inside a coil.

MDL News & Trends

MDL Continues Research on Extreme Environment Sensors

Field emission from carbon nanotube (CNT) bundles has been applied to develop a new class of vacuum microelectronics for harsh environment applications. CNTs have demonstrated superior field emission performance because of their low emission threshold and high current density, and are compatible for monolithic integration with silicon structures to develop microelectronic/microsensor systems. This technology is applicable to in situ sensor electronics for applications where the operating environment is high-temperature and high-pressure, and has corrosive chemicals.

The digital and analog electronic devices developed using CNT-vacuum microelectronic technology can be integrated with sensor systems to achieve prolonged stand-alone operation during exploration. High-performance cold cathodes using arrays of CNT bundles have exhibited robust operation in poor vacuums of 10–5 to 10–6 Torr, a typically achievable range inside hermetically sealed microcavities. By monolithically integrating CNT cathodes with micromachined Si multigate structures, MDL has demonstrated a new class of programmable “vacuum” logic gates and achieved switching operation at temperatures up to 700 °C. Work is ongoing to improve design and achieve vacuum packaging to make stand-alone devices for circuit board integration.

CNT-vacuum microelectronics opens up a new regime of in situ electronics for novel sensor/electronics systems because of their inherent high-temperature tolerance and corrosion resistance. Unlike traditional vacuum tubes, these are low-power, miniature, and potentially as fast as their solid-state counterparts while exhibiting superior reverse bias or leakage current characteristics. MDL’s research on extreme environment sensors and electronics knowledge has the potential for multiple applications ranging from commercial oil and gas exploration to studies on Venus.

Above: Carbon nanotube emitters integrated with extraction gate electrodes