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Jul 2nd, 2010
Highly sensitive THz detector employs GaN transistor
Panasonic has developed a GaN-based THz detector that is applicable to a variety of security or analysing systems, which will greatly help the wide-spread use of such THz applications in the future.
The company claims it to exhibit the highest sensitivity at room temperature of 1100V/W.
The GaN detector forms a so-called plasma wave of the electrons, in which the electron density is fluctuated as a wave. The plasma wave resonates with the incident THz wave, which is detected as an electric signal at the GaN transistor. The use of GaN with high electron velocity effectively increases the amplitude of the plasma wave and the extracted electric signal. The detector uses the gate electrode itself as a dipole antenna free from the loss in the transmission lines. In addition, the source and the drain electrodes of the GaN transistor are designed to work as parasitic elements for the antenna, which effectively confine the incident THz wave in the vicinity of the gate. Note that the employed MOS gate structure reduces the gate leakage current suppressing the leakage of the plasma wave around the gate antenna. The choice of the material together with a novel antenna structure successfully increases the sensitivity of the THz detector.
The fabricated THz detector using Panasonic's proprietary GaN technologies achieves a very high sensitivity of 1100V/W at room temperature, while a conventional detector utilising thermal conversion requires cooling of the device down to -270°C to maintain high enough sensitivity. The developed GaN-based THz detector free from such cooling systems can make the THz systems very compact keeping high sensitivity.
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