RESUMEN
High electron mobility transistors (HEMTs) have become important for high frequency and low noise applications. There are devices now operating with a cutoff frequency, f(T), of several 100 GHz. Through simulation, we have been investigating how these frequencies may be pushed even higher, and have found that it may be possible to achieve an f(T) of over 3 THz. For this, we have used a full-band, cellular Monte Carlo transport program, coupled to a full Poisson solver, to study a variety of InAs-rich, InGaAs pseudomorphic HEMTs and their response at high frequency, concentrating on devices with a structure (from the substrate) InP/InAlAs/InGaAs/InAlAs/InGaAs, with the quantum well composed of In(0.75)Ga(0.25)As. We have studied gate lengths over the range 10-70 nm and various source-drain spacings. The performance of scaled devices has been evaluated to determine the ultimate frequency limit. Here, the importance of the effective gate length has been evaluated from the properties internal to the device.
RESUMEN
We demonstrate the microfabrication of a low-noise silicon based device with integrated silver/silver chloride electrodes used for the measurement of single ion channel proteins. An aperture of 150 microm diameter was etched in a silicon substrate using a deep silicon reactive ion etcher and passivated with 30 nm of polytetrafluoroethylene via chemical vapor deposition. The average recorded noise in measurements of lipid bilayers was reduced by a factor of four through patterning of a 75 microm thick SU-8 layer around the aperture. Integrated electrodes were fabricated on both sides of the device and used for repeatable, stable, giga-seal bilayer formations as well as characteristic measurements of the transmembrane protein OmpF porin.
