A Japanese research team developed a resonant tunneling diode (RTD) device that operates at room temperatures and has a fundamental oscillation frequency of 1.42THz.

The team is led by Masahiro Asada, professor at the Quantum Nanoelectronics Research Center (QNERC) of the Tokyo Institute of Technology (Tokyo Tech). The development was announced at Tohoku University Dec 16, 2013.

An RTD is a two-terminal device having one quantum well, which can be obtained by, for example, using a semiconductor to form two energy barriers that are several nanometers away from each other. With an RTD, an area with a negative differential resistance appears in the current-voltage characteristics depending on the quantum level formed in the quantum well. Because an AC electric field is amplified in the area, an oscillator circuit can be realized by using an LC circuit, etc.

This time, the research team developed a device consisting of (1) an RTD that oscillates with a fundamental oscillation frequency of 1.42THz (electromagnetic wave) at room temperatures and (2) an antenna called "slot antenna." The fundamental oscillation frequency of the team's RTD device was 1.08THz until the summer of 2012. But it announced a 1.31THz device in September 2012, followed by the latest 1.42THz device.

For the new device, the team (1) narrowed the space between the two energy barriers, (2) optimized the distance between the electrode and battier on the side of the diode's collector and (3) formed a small energy barrier in front of the barrier on the side of the emitter. The first and second improvements shortened electron transit time and increased oscillating frequency while the third one reduced operating voltage, the team said.