Makoto Kasu

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During the past decade, research into superconducting quantum bits (qubits) based on Josephson junctions has made rapid progress. Many foundational experiments have been performed, and superconducting qubits are now considered one of the most promising systems for quantum information processing. However, the experimentally reported coherence times are(More)
Compact high-efficiency ultraviolet solid-state light sources--such as light-emitting diodes (LEDs) and laser diodes--are of considerable technological interest as alternatives to large, toxic, low-efficiency gas lasers and mercury lamps. Microelectronic fabrication technologies and the environmental sciences both require light sources with shorter emission(More)
Diamond possesses exceptional physical properties, such as a high breakdown field and carrier mobility. It is therefore expected to be highly efficient for high-power RF devices. We identify hole carrier doping in diamond using nitrogen dioxide (NO<sub>2</sub>). Furthermore, we find that an aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) passivation layer(More)
Using the nitrogen dioxide (NO<sub>2</sub>) adsorption and aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) passivation technique, we have solved the thermal instability problem of hydrogen-terminated (H-terminated) diamond field-effect transistors (FETs). The diamond FET showed high maximum I<sub>DS</sub> of -1.35 A/mm, cut-off frequencies, f<sub>T</sub> of 35(More)
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