Analysis of Fringing Effect on Resonant Plasma Frequency in Plasma Wave Devices

Abstract

We consider a single spike of ferrofluid, arising in a small cylindrical container, when a vertically oriented magnetic field is applied. The height of the spike as well as the surface topography is measured experimentally by two different technologies and calculated numerically using the finite element method. As a consequence of the finite size of the container, the numerics uncovers an imperfect bifurcation to a single spike solution, which is forward. This is in contrast to the standard transcritical bifurcation to hexagons, common for rotational symmetric systems with broken up-down symmetry. The numerical findings are corroborated in the experiments. The small hysteresis observed is explained in terms of a hysteretic wetting of the side wall.

Analysis of terahertz plasma resonances in structures with two-dimensional electron systems periodically modulated by interdigitated gate

“…If the structure contains N gate fingers G2 of length L g2 and N +1 gate fingers G1 of length L g1 the total number of such unit cells will be 2N plus two extreme unit cells each consisting of ungated region and gated region of the length L g1 / 2 on the right or left side. As it was shown by Nishimura et al, 10 fringing affects electric field distribution in the ungated region, which, in turn modifies the sheet electron density there. To find an electric field distribution along 2DEG channel in the unit cell with two gates and a charged sheet of ionized donors formed as a result of ␦-doping of the HEMT structure is quite a challenging problem.…”

“…4 and 5͒ due to fringing an electric field leaks out rather far from the edges of the gate contacts so that electron concentration in the fringed ungated 2DEG channel regions can be also controlled by the gate bias voltage. 10 Under such conditions to evaluate the impact of ungated 2DEG channel regions on plasma resonances we separate a structure which crossection is shown in Fig. 1͑b͒ into a number of unit cells.…”

Theoretical study of terahertz active transmission line oscillator based on RTD-gated HEMT

“…Under this condition, oscillation frequency will not increase as the device size decreases. 30 It needs advanced manufacturing processes to minimize parasitic capacitances to resolve this problem. As analysed above, oscillation arising from terahertz oscillator for plasma-wave HEMT should meet g max =-rc/l in terahertz frequency range.…”

Analysis of resonant MEMS based on high‐electron mobility transistor‐like structure

“…1c. To calculate spatial distribution of the electric field we generalized the formalism presented in [6], [7] for the case of the structure with double layers characterizing by different dielectric constants. As thickness d a of the air gap between cantilever and top semiconductor layer is usually larger than the thickness d g of the latter one may assume that lateral spreading of the electric field due to fringing is determined mainly by the air gap so that further fringing in the semiconductor layer can be neglected.…”

“…1c due to the bias voltage V c (t). To calculate it in the presence of electric field fringing we used the concept of gate "extension" [7]. In the linearized form this force is given by expression:…”