454 research outputs found
Scaling study of Si/SiGe MODFETs for RF applications
Based on the successful calibration on a 0.25 /spl mu/m strained Si/SiGe n-type MODFET, this paper presents a gate length scaling study of double-side doped Si/SiGe MODFETs. Our simulations show that gate length scaling improves device RF performance. However, the short channel effects (SCE) along with the parasitic delays limit the device performance improvements. We find that it is necessary to consider scaling (dimensions and doping) of both the lateral and vertical architecture in order to optimize the device design
A SiGe HEMT Mixer IC with Low Conversion Loss
The authors present the first SiGe HEMT mixer integrated circuit. The active mixer stage, operating up to 10GHz RF, has been designed and realized using a 0.1” ”” ”m gate length transistor technology. The design is based on a new large-signal simulation model developed for the SiGe HEMT. Good agreement between simulation and measurement is reached. The mixer exhibits 4.0dB and 4.7dB conversion loss when down-converting 3.0GHz and 6.0GHz signals, respectively, to an intermediate frequency of 500MHz using high-side injection of 5dBm local oscillator power. Conversion loss is less than 8dB for RF frequencies up to 10GHz with a mixer linearity of â8.8dBm input related 1dB compression point
Thermopower-enhanced efficiency of Si/SiGe ballistic rectifiers
Injection-type ballistic rectifiers on Si/SiGe are studied with respect to
the influence of gate voltage on the transfer resistance RT (output voltage
divided by input current) for different positions of a local gate electrode.
The rectifiers are trifurcated quantum wires with straight voltage stem and
oblique current-injecting leads. Depending on the gate configuration,
thermopower contributions arise from nearly-pinched stem regions which either
cancel each other or impose upon the ballistic signal with same or opposite
polarity. At best, this enhances RT to a maximum value of 470 Ohm close to
threshold voltage
Optimizations of sub-100 nm Si/SiGe MODFETs for high linearity RF applications
Based on careful calibration in respect of 70 nm n-type strained Si channel S/SiGe modulation doped FETs (MODFETs) fabricated by Daimler Chrysler, numerical simulations have been used to study the impact of the device geometry and various doping strategies on device performance and linearity. The device geometry is sensitive to both RF performance and device linearity. Doped channel devices are found to be promising for high linearity applications. Trade-off design strategies are required for reconciling the demands of high device performance and high linearity simultaneously. The simulations also suggest that gate length scaling helps to achieve higher RF performance, but decreases the linearity
Reduced 1/f noise in p-Si0.3Ge0.7 metamorphic metalâoxideâsemiconductor field-effect transistor
We have demonstrated reduced 1/f low-frequency noise in sub-”m metamorphic high Ge content p-Si0.3Ge0.7 metalâoxideâsemiconductor field-effect transistors (MOSFETs) at 293 K. Three times lower normalized power spectral density (NPSD) SID/ID2 of drain current fluctuations over the 1â100 Hz range at VDS = â50 mV and VGâVth = â1.5 V was measured for a 0.55 ”m effective gate length p-Si0.3Ge0.7 MOSFET compared with a p-Si MOSFET. Performed quantitative analysis clearly demonstrates the importance of carrier number fluctuations and correlated mobility fluctuations (CMFs) components of 1/f noise for p-Si surface channel MOSFETs, and the absence of CMFs for p-Si0.3Ge0.7 buried channel MOSFETs. This explains the reduced NPSD for p-Si0.3Ge0.7 MOSFETs in strong inversion
Quantum interference effects in p-Si1âxGex quantum wells
Quantum interference effects, such as weak localization and electronelectron interaction (EEI), have been investigated in magnetic fields up to 11 T for hole gases in a set of Si1âxGex quantum wells with 0.13 < x < 0.95. The temperature dependence of the hole phase relaxation time has been extracted from the magneto-resistance between 35 mK and 10 K. The spin-orbit effects that can be described within the Rashba model were observed in low magnetic fields. A quadratic negative magneto-resistance was observed in strong magnetic fields, due to the EEI effect. The hole-phonon scattering time was determined from hole overheating in a strong magnetic field
From an extremophilic community to an electroautotrophic production strain: identifying a novel Knallgas bacterium as cathodic biofilm biocatalyst
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