3,613 research outputs found
Seventy Years of Getting Transistorized
Vacuum tubes appeared at the break of the twentieth century giving birth to electronics. By the 1930s, they had become established as a mature technology, spreading into areas such as radio communications, long distance radiotelegraphy, radio broadcasting, telephone communication and switching, sound recording and playing, television, radar, and air navigation. During World War II, vacuum tubes were used in the first electronic computers, which were built in the United Kingdom and the United States. Although vacuum tubes had been a successful technology, they were also bulky, fragile and expensive, had a short life, and consumed a lot of power to heat the thermo-emitters. These drawbacks promoted the search for completely new devices. Alternative solutions had long been considered, but without significant developments
High-frequency two-input CMOS OTA for continuous-time filter applications
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Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier
Permalloy magnetic tunnel junctions. Complementary low frequency noise
measurements are used to understand the conductance results. The obtained data
indicate the breakdown of the Coulomb blockade for thickness of the asymmetric
silicon layer exceeding 1.2\AA . The crossover in the conductance, the
dependence of the tunnelling magnetoresistance with the bias voltage and the
noise below 80K correspond to 1 monolayer coverage. Interestingly, the zero
bias magnetoresistance remains nearly unaffected by the presence of the silicon
layer. The proposed model uses Larkin-Matveev approximation of tunnelling
through a single impurity layer generalized to 3D and takes into account the
variation of the barrier shape with the bias voltage. The main difference is
the localization of all the impurity levels within a single atomic layer. In
the high thickness case, up to 1.8\AA, we have introduced a phenomenological
parameter, which reflects the number of single levels on the total density of
silicon atoms.Comment: 10 pages, 13 figure
Correlation effects and spin dependent transport in carbon nanostructures
The impact of symmetry breaking perturbations on the spin dependent transport
through carbon nanotube quantum dots in the Kondo regime is discussed.Comment: 10 pages, 6 figure
Why ferromagnetic semiconductors?
Rapid development of information technologies originates from the exponential
increase in the density of information that can be processed, stored, and
transfer by the unit area of relevant devices. There is, however, a growing
amount of evidences that the progress achieved in this way approaches its
limits. Various novel ideas put forward to circumvent barriers ahead are
described. Particular attention is paid to those concepts which propose to
exploit electron or nuclear spins as the information carriers. Here,
ferromagnetic semiconductors of III-V or II-VI compounds containing a sizable
concentration of transition metals appear as outstanding spintronic materials.Comment: 8 PDF pages, Polish Physical Soc. Meetin
Space station power semiconductor package
A package of high-power switching semiconductors for the space station have been designed and fabricated. The package includes a high-voltage (600 volts) high current (50 amps) NPN Fast Switching Power Transistor and a high-voltage (1200 volts), high-current (50 amps) Fast Recovery Diode. The package features an isolated collector for the transistors and an isolated anode for the diode. Beryllia is used as the isolation material resulting in a thermal resistance for both devices of .2 degrees per watt. Additional features include a hermetical seal for long life -- greater than 10 years in a space environment. Also, the package design resulted in a low electrical energy loss with the reduction of eddy currents, stray inductances, circuit inductance, and capacitance. The required package design and device parameters have been achieved. Test results for the transistor and diode utilizing the space station package is given
Development of deep submicron CMOS process for fabrication of high performance 0.25 nm transistors
An advanced process for fabrication of 0.25 ÎŒm CMOS transistors has been demonstrated. This process is designed for transistors with Lpoly = 0.25 ÎŒm and Leffective = 0.2 um on 150 mm (6â) silicon wafers. Devices with Leffective of 0.2 um and smaller have been tested and found operational. A 0.25 um NMOS transistor with drain current of 177 ÎŒA/ÎŒm at VG=VD=2.5 V and a PMOS transistor with drain current of 131 ÎŒA/ÎŒm at VG=VD=-2.5 V are reported. The threshold voltages are 1.0 V for the NMOS and -0.735 V for the PMOS transistors. These 0.25 um NMOS and PMOS are the smallest transistors ever fabricated at RIT. Many processes have been integrated to produce the final CMOS devices, including: 50 Ă
gate oxide with N2O, shallow trench isolation by chemical mechanical planarization (CMP), dual doped polysilicon gates for surface channel devices, ultra-shallow low doped source/drain extensions using low energy As and BF2 ions, rapid thermal dopant activation, Si3N4 sidewall spacers, TiSi2 salicide source/drain contacts and gates, uniformly doped twin wells, contact cut RIE and 2 level aluminum metallization
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