The operational temperature range of Silicon (Si) devices is typically limited to temperatures below ~300°C. However, researchers from the University of Tsukuba succeeded in achieving stable operation of diodes at 827°C and transistors at 727°C using aluminum nitride (AlN) semiconductors.

Tsukuba, Japan—Silicon (Si) semiconductors are ubiquitous in electrical appliances and play an essential role in our daily lives. However, in high-temperature environments exceeding 300°C, such as underground resource drilling, space exploration, and engine peripherals, improved semiconductor materials are required because of the limited operational temperature range of Si devices.

Wide-bandgap semiconductors are preferable for high-temperature electronics. Currently, aluminum nitride (AlN) crystals are among the most attractive materials for high-temperature devices because they possess larger bandgap energy in comparison to other semiconductors. Numerous studies have reported AlN diodes and transistors that can operate at temperatures above room temperature. However, the maximum operating temperatures of these AlN devices are limited to 500°C or lower owing to technical problems associated with electrical characterization systems.

This study presents the fabrication and evaluation of high-quality AlN-layered diodes and transistors using a novel electrical characterization system capable of functioning at temperatures up to 900°C. The researchers achieved a successful demonstration of diode operation at 827°C, surpassing all previous records, and the transistors operated at 727°C. Furthermore, nickel electrodes in AlN devices remained stable even at 827°C. Notably, these AIN devices are practically feasible because the AlN layers are grown on large, low-cost sapphire substrates. Moreover, the AlN devices exhibited a simple structure.

This research has paved the way for operable semiconductor devices to operate in severe environments (>800°C). These AlN devices are expected to be employed in high-temperature industries such as underground mining, steel production, space exploration, and aviation.

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This work was financially supported by JSPS KAKENHI Grant Nos. 19H02166 and 23H01863, DOWA Techno Fund (http://www.dowa-technofund.jp/en/) under collaboration with DOWA ELECTRONICS MATERIALS CO., LTD., and the Top Runners in the Strategy of Transborder Advanced Research (TRiSTAR) program conducted as the Strategic Professional Development Program for Young Researchers by the MEXT.

Original Paper

Title of original paper:

Temperature dependence of electrical characteristics of Si-implanted AlN layers on sapphire substrates

Journal:

Applied Physics Express

DOI:

10.35848/1882-0786/acdcde

Correspondence

Assistant Professor OKUMURA Hironori
Institute of Pure and Applied Science, University of Tsukuba

Related Link

Institute of Pure and Applied Sciences