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Item type:Publication, Access status: without files , Integration and characterisation of Schottky diodes with a pre-amplifier for THz applications(2020-11-08); ; ; This contribution deals with the investigation and characterisation of fully integrated broadband Terahertz (THz) Schottky diodes using silver (Ag) metallic nanowires (NWs) with 120 nm diameter as bridge contacts for zero-bias operating THz detectors based on highly doped Gallium Arsenide (GaAs) and Indium Gallium Arsenide (InGaAs) layers. The combination of InGaAs and metallic NWs shows almost 7 times higher forward current than the metallic NW with GaAs at 0.27 V with a capacitance of 0.5 fF and a series resistance of 29Omega. The highest calculated cut-off frequency of 10.7 THz was obtained for a NW contacted vertical InGaAs diode.Publicationtype: Conference Paper32 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fabrication and characterization of high power Gallium Nitride based terahertz Gunn diodes(2020-11-08); ; ; ; In this paper, we report the fabrication and characterization of a THz Gunn source based on Gallium Nitride (GaN) with side-contact and field-plate technologies. This source works stable at operating voltages up to 20 V due to good passivation layer and good heat sink to the GaN substrate. The GaN-based Gunn diode has relatively high forward current of 0.9 A and a high current drop of about 50 mA for higher frequency and output power.Publicationtype: Conference Paper37 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Reliable GaN-based THz gunn diodes with side-contact and field-plate technologies(IEEE, 2020-04-29); ; ; ; For the first time, Gallium Nitride(GaN)-based Gunn diodes with side-contact and field-plate technologies were fabricated and measured with reliable characteristics. A high negative differential resistance (NDR) region was characterised for the GaN Gunn effect using side-contact technology. The I-V measurement of the THz diode showed the ohmic and the Gunn effect region with high forward current of 0.65A and high current drop of approximately 100mA for a small ring diode width w of 1.5 μm with 600 nm effective diode height h at a small threshold voltage of 8.5V. This THz diode worked stable due to good passivation as protection from electro-migration and ionisation between the electrodes as well as a better heat sink to the GaN substrate and large side-contacts. The diodes can provide for this thickness a fundamental frequency in the range of 0.3 - 0.4 THz with reliable characteristics.Publicationtype: Journal ArticleScopus© Citations 21 129 221 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Experimental Investigation of Graphene Layers as 2D Nanoelectrode for Continuous Wave Terahertz GenerationThe effect of using graphene as 2D nanoelectrode for continuous wave (CW) terahertz (THz) photomixers were investigated. The multilayer graphene (6-8 and 3-5 MLG) sheets were used as six-finger interdigital nanoelectrodes on a low-temperature-grown (LTG) GaAs photoconductor. The MLG nanoelectrode shows unique properties with high short-circuit current capabilities and reliable high photocurrents. The number of graphene layers play a big role on the electrical and the optical properties of graphene nanoelectrode. In one hand, a thinner graphene increases the transparency of the nanoelectrodes to improve the power conversion efficiency, and on the other hand, a thicker graphene is required to carry high current densities and enhance the photomixer performance.Publicationtype: Conference Paper41 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Sliver nanowire surface plasmon polaritons enhancement in terahertz nanodevices(2019-09-01); ; ; ; New types of continuous-wave (CW) THz photomixers were fabricated using a silver nanowire (Ag-NW) as nanocontact on low-temperature-grown (LTG) and nitrogen-ion-implanted GaAs, respectively. The Ag-NW nanoelectrodes produced a large reduction of the device capacitance and a significant enhancement of the photocurrent as compared to conventional photomixers. The combination of very low capacitance and high photocurrent are shown reliable and efficient THz generation in the upper part of the broad spectral THz range. The main enhancement is shown from the wave patterns of surface plasmon polaritons (SPPs) on the Ag-NW which are measured using a scattering-type Scanning Near-field Optical Microscope (s-SNOM)Publicationtype: Conference Paper47 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Interdigital multilayer-graphene nanoelectrodes for continuous wave terahertz photomixersA new type photomixer for continuous wave (CW) terahertz (THz) generation was fabricated using 6-8 layer graphene. The multilayer graphene (MLG) sheets were used as six-finger interdigital nanoelectrodes on a low-temperature-grown (LTG) GaAs photoconductor. The MLG nanoelectrode shows unique properties with high short-circuit current capabilities and reliable high photocurrents. Furthermore, due to the transparency of the graphene, the use of graphene as nanoelectrodes in THz photomixers allows an efficient optical power illumination for high photocurrent generation and shows a promising CW THz emission.Publicationtype: Conference Paper71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , SiC-SiO2 MEMS-DBR based widely tunable optical filters around 1550 nm with narrow FWHMEver growing optical data transmission networks and miniaturization of spectroscopic equipment demand for small, energy efficient and mass-produced optical components. Here we present distributed Bragg reflector (DBR) mirror based widely tunable optical Fabry-Perot filters comprising a novel material combination namely, silicon carbide (SiC) and silicon dioxide (SiO ) layers with refractive indices of 2.46 and 1.45, respectively. The resulting refractive index step of 1, provides high reflectivites (>99.5 %) with wide stopbands of more than 300 nm [1]. Hence, large wavelength tuning range and a narrow full width at half maximum (FWHM) filtered signals can be produced. Structuring the dielectric layers by surface micromachining creates a free standing movable mirror supported by four beams. Due to inherent stress created during low-temperature plasma enhanced chemical vapor depositions (PECVD) we obtain a tunable stable plane concave resonator. In the end the cross section of a filter shows a fixed bottom DBR deposited on a silicon substrate, a tunable airgap and an electrothermally actuated top MEMS DBR with a gold electrode for heating current I . On the substrate backside where the filtered signal is exiting an anti-reflection coating is deposited.Publicationtype: Conference Paper42