The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The introduction of advanced Multistage Depressed Collectors (MDC) to high-power fusion gyrotrons will be the key to increase the gyrotron overall efficiency above 60 % as required for future DEMOnstration power plant. MDCs which base on the E×B drift concept might solve the fundamental issue of handling the secondary electrons. To consider the effect of secondary electrons in a stationary state,...
Plasmonic contact electrodes are very effective for enhancing the radiation power of photoconductive terahertz sources. Au is a preferred metal for plasmonic contact electrodes due to the high plasmonic enhancement factors it offers in the near-infrared regime. However, Au requires an adhesion layer to stick well to photoconductive substrates. We investigate the impact of the Au adhesion layer on...
The key to increase the gyrotron efficiency to a level significantly higher than 50% is the development of a highly efficient collector system for the recovery of the spent electron beam energy. In this context, a significant effort has been dedicated at KIT during the last years in order to design a reliable, robust and efficient multistage collector system. For this purpose several design approaches...
A novel geometry of self-switching diode (SSD) is presented: the W-Shape geometry. A numerical model to evaluate the DC performance of the W-Shape SSD fabricated on AlGaAs/GaAs heterostructures that contains a two-dimensional electron gas (2DEG) is employed by the manipulation of the surface-states in the device. With this geometry the possibility of modifying the charge distribution in the nano-channel...
Excitation of various resonance modes in a square open-loop resonator was studied by Josephson spectroscopy. A copper resonator with a side of a square of 233 μm was fabricated. Changing the position of the resonator with respect to a bicrystal YBa2Cu3O7−x Josephson junction, a number of resonances was observed in measured spectra with the center frequencies from 78 GHz to 218 GHz. Measured data were...
A new type of continuous-wave (CW) terahertz (THz) photomixer was fabricated using a nitrogen-doped single layer graphene (N+SLG) powder and silver nanowire (Ag-NW of Ø 300 nm) on low-temperature-grown (LTG) GaAs. The new hybrid (N+SLG/Ag-NW) structure provides simple fabrication steps and better performance in terms of high current handling together with reliable operation. The THz output power itself...
We report on a novel type of a room-temperature terahertz (THz) detector using a single walled carbon nanotube (SWNT) film, which is based on detection mechanism of the photothermoelectric effect. Enhancing difference in the Seebeck coefficient between two adjacent materials is a key technique for improving the detection sensitivity. In this work, we fabricated a p-n junction in the SWNT film by dropping...
We have performed terahertz (THz) spectroscopy to detect ultrafast motion of a single atom in a single endohedral metallofullerene Ce@C82 molecule. Using the source and drain electrodes separated by a sub-nm gap, we focus THz radiation onto a single Ce@C82 molecule trapped by the nanogap electrodes. When the molecule is illuminated with THz radiation, THz-induced photocurrent is observed. We explain...
We achieved frequency increase in resonant tunneling diode terahertz oscillator by reducing conduction loss in the slot antenna with thick antenna electrode. By a graded increase in electrode thickness for 0.1, 1, 2, and 3 μm, increase in oscillation frequency was obtained. A highest oscillation frequency of 1.98 THz was achieved with an optimum electrode thickness of 2 μm.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.