A new model is presented for the calculation of passive intermodulation (PIM) in waveguide connections. The considers roughness interconnecting surfaces and presence an insulator layer (oxide contaminants) on these metal surfaces. This results generation a contact resistance, which can excite PIM level. In particular, case metal-insulator-metal regions are source especially investigated. level response calculated different junction parameters like applied mechanical load, surface finish, or...

In this paper, the generation of passive intermodulation at rectangular waveguide flange bolted connections is investigated.An exhaustive series tests has been performed in order to provide understanding on physics lying behind such a phenomenon.In particular, response system studied as function applied torque screws.It found that, some situations, differs from its expected behavior.An interpretation discrepancies given, and practical guidelines for design flanges free are provided well.

We report on a numerical study of the characteristics p-GaN/n-ZnO light-emitting diodes (LEDs) with p-NiO and n-ZnSe interlayers, LED design optimization which includes bandgap engineering, thickness doping constituent layers. The current-voltage dependences investigated LEDs show threshold voltage 3.1 V, 5.4 V 5.6 for devices without presence respectively. It is found that p-NiO, n-ZnO interlayers act as an electron blocking layer, active media transport established insertion both leads to...

Porous GaP layers prepared by electrochemical dissolution of (100)-oriented bulk material have been studied micro-Raman spectroscopy. The anodization causes a breakdown the polarization selection rules, inherent to (100) surface, accompanied downward shift LO-phonon frequency and appearance surface-related vibrational mode in gap between optical phonons. was found decrease from 398 394.3 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ with increasing current. A Raman line-shape analysis based on...

Electrochemical etching techniques were used to fabricate semiconductor sieves of gallium phosphide, i.e., two-dimensionally nanostructured membranes exhibiting an enhanced optical second harmonic generation (SHG) in comparison with the bulk material. The SHG rotational and fundamental polarization dependencies studied under sample excitation by a 1064-nm Nd-YAG laser beam indicate homogeneity uniaxial symmetry membranes. artificial anisotropy nonlinear response induced nanotexturization...

In this paper the multipactor power threshold in arbitrary complex components based on rectangular waveguide technology is investigated. The two required computations when studying such a phenomenon have been performed: calculation of electromagnetic fields inside component and determination breakdown onset itself. A full model described tested for particular set devices which experimental measurements also performed. good agreement between predicted values results shows validity approach followed.

Porous GaP, InP and GaAs structures fabricated by MeV ion-implantation-assisted electrochemical etching were investigated Raman Fourier transform infrared spectroscopy. Fröhlich modes in the frequency gap between transverse optical longitudinal frequencies observed their longitudinal-transverse splitting was established. The frequency-dependent properties region calculated using a dielectric function derived on basis of an appropriate two-dimensional effective-medium theory. theoretical...

New types of continuous-wave (CW) terahertz (THz) photomixers were fabricated using 1-D and 2-D nanocontacts on low-temperature-grown (LTG) GaAs as well nitrogen-ion-implanted (N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> i) GaAs. The formed by silver nanowires graphene sheets, respectively. A nanowire (Ag-NW) with a physical diameter \varnothing 60 nm 120 can handle currents , respectively, without electromigration, thus enabling...

Porous layers fabricated by anodic etching of n-GaP substrates in a sulfuric acid solution were studied electron microscopy and cathodoluminescence (CL) microanalysis. The morphology porous was found to depend strongly upon the anodization conditions. When process starts at initial surface, “catacomb-like” pores current-line oriented are introduced low high current densities, respectively. After development either kind pore, further density about 1 mA/cm2 favors propagation along 〈111〉...

The spectral characterization of a broadband antenna using pump-probe photomixing continuous-wave (CW) terahertz (THz) system is presented. high dynamic range the system, comparable to or better than that similar systems reported in literature, provides an accurate means characterization. planar exhibits log-periodic behavior at low frequencies, bow-tie and resonance characteristic between, well agreement with geometry. It predicted improved geometry extends higher frequencies would...

Electro-optical control of the terahertz phase in continuous-wave photomixing systems allows determination both amplitude and with a single sampling point per frequency. It is experimentally demonstrated that spectroscopic measurements can be performed by an order magnitude faster method without performance degradation compared to standard delay line technique.

Abstract The possibility of high frequency electromagnetic wave generation by field emission based devices has great interest. wide bandgap materials GaN and AlGaN are very promising for these applications due to low electron affinity the existence satellite valleys in conduction band. results investigations peculiarities from nanostructured surfaces presented. Multilayer structures with various levels layer doping on sapphire bulk substrates were used as initial wafers. surface upper layers...

A Schottky diode based module for direct detection of THz power provides fast measurement capabilities at room temperature. This paper presents the broadband spectral characterization a in comparison to Golay cell frequency range from 0.1 up 2 THz.

We report on high‐responsivity, fast near‐ultraviolet photodetectors based bulk ZnSe employing a metal–semiconductor–metal structure with and without interdigital contacts. A very high responsivity of 2.42 4.44 W −1 at 20 V bias voltage rejection rate 7900 4810 for the light wavelength 325 nm is obtained contacts, which indicates an internal gain. The mechanism gain attributed to impact ionization atoms under electric field strength 133 kV cm . Also low dark current ≈3.4 nA detectivity ≈1.4...

A sharp increase of the emission current at high electric fields and a decrease threshold voltage after pre-breakdown conditioning diamond-like carbon (DLC) films have been measured. This effect was observed for DLC-coated silicon tips GaAs wedges. During electron field (EFE) energy barriers caused by an sp3 phase between sp2 inclusions can be broken, resulting in formation conducting nanochannels semiconductor–DLC interface surface DLC film. At densities local heating, transforms into...

A method of electro-optical control the terahertz (THz) phase in continuous-wave photomixing THz systems is suggested and demonstrated. The enables phase-sensitive detection without any moving mechanical components system. Additionally, allows lock-in a chopper, which increases signal-to-noise ratio

We identified conditions for room-temperature operation of terahertz quantum cascade lasers (THz QCLs) where variable barrier heights are used on ZnSe/Zn1–xMgx Se material systems. The THz QCL devices based three-level two-well design schemes. with alternating barriers different were compared laser structures fixed heights. It is found that the device novel employing achieved emission about 1.45 at (300 K), and has improved performance due to suppression thermally activated carrier leakage...