Edmundo A. Gutierrez-D

Interaction of Powerful Electromagnetic Wave with Integrated P-I-N Structures

Theoretical and experimental analyze of surface-oriented silicon p-i-n structures for the control of high power wideband devices, are introduced. The structure here studied show good operating characteristics under the application of powerful electromagnetic waves. These surface-oriented structures are very promising for applications in the millimeter- and submillimeter-wave range.

A Silicon Plasma-Based Wideband Modulator

Theoretical and experimental analysis has been performed for surface oriented silicon plasma-based p,i,n structures used to control high power level, broadband devices. It is shown that these structures are very promising for their use as modulators in the millimeter and submillimeter wave range.

Non-homogeneous space mechanical strain induces asymmetrical magneto-tunneling conductance in MOSFETs

Through the measurement of the magneto-conductance properties of the reverse-biased Drain-Bulk (DB) junction of a MOSFET, we found the conductance of the active channel region, nearby the DB junction, is not space homogeneous, but it shows better conductance properties towards the edges than in the middle of the channel. Such a non-homogeneous channel conductance is attributed to the asymmetrical distribution of the mechanical strain used to enhance the carrier mobility.

Generation of short light pulses under the stimulated Brillouin scattering in fibers with an optimal feedback

The generation of short light pulses (≤1 ns) in single mode fibers under pumping by wide laser pulses (of a microsecond duration) due to the backward stimulated Brillouin scattering (SBS) is numerically investigated. The influence of the acoustic diffraction is taken into account. The cases of acoustic waveguide and anti-waveguide fibers are considered. For an acoustic anti-waveguide fiber, a dependence of overlap integral S on the acoustic mode number n has a sharp peak in the region of n ∼ 100. Computer simulations have demonstrated the energy conversion of the pump wave into short pulses of the signal (Stokes) wave in the case of synchronous pumping. The optimal length of the fiber should be approximately equal to the half-length of the pump pulse. The bypass time of the Stokes pulse of the optimal circuit fiber and the feedback loop must be equal to the repetition period of the pump pulse. An importance of acoustic mode structure of the fiber for the process of forming pulse train in shown. We have found that the acoustic anti-waveguide fibers with a small core (a < 3 μm) can be preferable for obtaining the stable train of compressed pulses.

An alternative method to monitor and control the IC temperature in the 4.2-77 K range

We introduce an alternative to the diode-method to monitor and control the local temperature in CMOS integrated circuits operated at cryogenic temperatures. We use an n-MOS transistor as a thermometer and prove that it has a linear performance in the 4.2 77 K temperature range. The method has been validated with a CMOS inverter fabricated in a 0.7 μm CMOS technology.

Thermo-Magnetic Effects in Nano-Scaled MOSFET: An Experimental, Modeling, and Simulation Approach

A numerical simulation methodology for incorporating thermo-magnetic effects on the MOSFET gate tunneling current is introduced. The methodology is based on the solution of the Schrödinger-Poisson coupled system, which allows simulating the influence of a static magnetic field and temperature on the wave functions and gate tunneling current of MOSFET devices. In addition to the preliminary results on the simulation methodology, experimental results on the effect of the magnetic field on the subthreshold slope, the off-current, and transconductance, are also introduced. The proposed simulation methodology, in conjunction with experimental data, is useful for device degradation and reliability studies in nano-scaled MOSFET devices. This experimental characterization technique sets also the basis for the development of a magnetic force nanoscopy technique, where the conductive properties, thanks to the Lorentz force, can be two-dimensionally mapped over the nano-scaled MOSFET channel plane.

Gate current tunneling modulated by magnetic field in 65nm nMOSFET's

An alternative characterization technique for ultra-thin gate oxides unveils that a magnetic field, applied parallel to the surface and perpendicular to the channel current, modulates both gate oxide tunneling and channel current. This is attributed to magnetic modulation of both quantum confinement and the Si-SiO2 potential barrier of a MOSFET. This new characterization technique serves to study the physics behind gate oxide tunneling [1], carrier quantization at the inversion/accumulation layers [2], and other effects at the Si-SiO2 interface of ultra-thin gate oxide MOSFETs, which add and extended characterization capability to pure electrical characterization techniques. The measured gate current Ig of a (W/L)=(2μm/65nm) nMOS transistor, with a gate oxide thickness of 1.9 nm, and exposed to a magnetic field B of +/-25 mili-Teslas (mT), is shown in Figure 1. The difference of the Ig current at B=+/-25 mT minus Ig at B=0 mT, here called AIg, is plotted in the right axis. A +Bz implies a magnetic field coming into the device, and a negative -Bz coming out the device. In this case a +Bz field implies the carrier distribution peak is pushed away from the Si-SiO2 interface, which lowers the tunneling probability by increasing the tunneling distance. On the other hand, because of the quasi-bond states of the quantized inversion channel, the potential barrier height reduces. These two quantum mechanisms play against each other giving an instable behavior for Vg>0.75 V as seen in Figure 2 where the differential channel current AId (Id at B=+/− 25mT minus Id at B=0 mT) is plotted versus Vg. The inverted electron distribution peaks is pushed down away of the interface (for +Bz), which in turns reduces surface carrier scattering giving a net increase of Id. Note that for Vg>0.75 V, when the AIg current becomes instable, the AId current has an inflection point. At this Vg point both the lowering of the tunneling probability and the potential barrier height starts to compete against each other. The redistributed electron inverted distribution dominates over the carrier mobility resulting in a AId roll-off In order to verify the analysis resulted from the experiments, a set of 3D numerical electro-magnetic simulations were preformed with Minimos-NT [3, 4]. The results are shown in Figure 3. The simulation software is set to account for models of direct tunneling in the channel, tunneling at the gate-drain/source edges, and energy quantization at the inversion and accumulation layers (gate-source/drain overlapping regions). To reproduce the experimental results the centroid peak (yp) of the inversion layer was adjusted from 0.5 nm (continuous line) to 0.75 nm (dashed line). This simulation confirms that energy quantization, and thus the electron inversion distribution peak, and tunneling probability are correlated to each other. The measured and simulated results for different magnetic field intensities and bias conditions are shown in Figure 4. The AId-Bz curve has a parabolic behavior, where the channel resistance is proportional to [1+((q/m∗)xBz)2]. Where ris the scattering time. The interplay of the carrier distribution and carrier mobility makes the maximum of the parabolic curve to shift to higher magnetic fields for larger Vd voltages. m∗ is the effective mass. The fluctuation of the gate current respect to Bz has a small dependence on the drain voltage. Further detailed measurements show the minimum magnetic field Bz that this MOSFET is able to detect is around 500 micro-Teslas. This magnitude is quite well within the range of on-chip generated magnetic fields [5], which is an indication that on-chip magnetic fields are self-inducing both channel current interference and gate leakage current.

Vacuum-silicon solid microwave diodes and triodes based on P++–N and on tungsten cathodes

Abstract This work reports the analysis of vacuum-solid microwave diodes and triodes. It shows the possibility to use these devices as amplifiers and generators in millimetre and submillimetre ranges. It is also possible to create multipliers with a large multiplication factor and small losses of the multiplication. In addition, the analysis of the basic parameters of these vacuum-solids microwave diodes with different types of cathodes shows that the diodes with a back voltage P ++ –N cathode have a wide frequency band, but an efficiency smaller than that of the tungsten diodes.

Quasi-Optical Sensors for Investigation of Acousto-Electromagnetic Phenomena of Popocatepetl Volcano

This article focuses on meteorological electronics based on the space research of acoustic-electromagnetic phenomena caused by Popocatepetl volcano (Mexico). The main purpose is to present two different types of quasi-optical sensors, one of them is formed by a modulator based on a surface oriented p,i,n structure with “deep” junctions; and by a silicon detector (avalanche photodiode with separated regions of absorption and multiplication: APDSAM). This system guarantee both good sensibility and wide range of sensing, sub-millimeter and millimeter range. This sensor has the advantage that can be realized as a planar array. On the other hand, for the remote measurement of basic meteorological parameters and chemical state by means of radiobrightness temperatures (radiometer systems) a low noise receiver on the base of dielectric waveguide and Schottky diodes cooled by means of cryoelectronic element is used.