We report on the room-temperature electrical rectification at 1.5 THz of a unipolar nanodiode based on symmetry breaking in a nanochannel. The exploitation of its nonlinear diodelike characteristic and intrinsically low parasitic capacitance enables rectification at ultrahigh speed. The zero-voltage threshold and unique planar layout make the nanodiode suitable for building large arrays. This is the highest speed reported in nanorectifiers to date.

Unipolar nanodiodes, also known as self-switching devices, have recently been demonstrated as terahertz detectors at room temperature. Here, we study their low-frequency noise spectra and noise equivalent power and show that both performance parameters are comparable to those reported for state-of-the-art Schottky diodes. The truly planar nanodiode layout enables building structures with thousands of devices connected in parallel, which reduce low-frequency noise without affecting sensitivity. The observed 1/f noise can be described by Hooge’s mobility fluctuation theory.

A ballistic-electron transport-based semiconductor nanorectifier, also known as a ballistic rectifier, has been demonstrated to have an intrinsic zero threshold voltage. In this paper, we characterize its low-frequency noise properties and show that the zero-threshold property enables elimination of the flicker noise. As a potential terahertz detector, the ballistic rectifier exhibits a noise equivalent power in the range of commercially available, uncooled thermal terahertz detectors. The observed noise in the device at finite biases is modeled quantitatively. The derived simple formula reveals that the narrowest part of the electron channels has a dominant role in the device noise properties.

Bamboo charcoal was produced by pyrolysis or carbonization process with extraordinary properties such as high conductivity, large surface area and adsorption property. These properties can be improved by activation process that can be done thermally or chemically. In this paper, carbonization and activation process of bamboo, its structural and adsorption properties will be presented. Herein, the adsorption properties of bamboo charcoal that has fully utilized in solar cell as the electrode, adsorbent for water purification and electromagnetic wave absorber are reviewed.

We report on the low-temperature detection of free-space radiation at 1.5 THz using a unipolar nanodiode, known as the self-switching diode (SSD), coupled with a spiral microantenna. The SSD, based on an asymmetric nanochannel, has a diode-like characteristic that can be utilized in rectifying high-frequency electrical signals. The truly planar structure of the SSD not only provides intrinsically low parasitic capacitance that enables rectification at ultrahigh speed, but also allows the fabrication of a large SSD array in parallel without the need for interconnection layers. The extrinsic voltage responsivity of the SSD-based detector achieved was ~15.6 V/W, but the estimated intrinsic voltage responsivity was ~45 kV/W.