User:John R. Brews

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Revision as of 22:08, 21 February 2011 by imported>John R. Brews (→‎Images)
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I am a Professor Emeritus of Electrical Engineering from The University of Arizona, where I taught device physics and circuit design for just under two decades. Previously, I was a research scientist for twenty-odd years at Bell Laboratories, Murray Hill, doing theoretical work in the areas of solid-state physics and device physics. I also am a Fellow of the IEEE, and a recipient of the Electron Device Society distinguished service award for work as Editor-in-chief of the journal IEEE Electron Device Letters, founded by Nobel prize winner George E. Smith. I've published a number of technical books and papers, some of which may be found at this link.


Images

Magnetism
B-field lines near uniformly magnetized sphere
(CC) Image: John R. Brews
B-field lines near uniformly magnetized sphere
Magnetic flux density vs. magnetic field in steel and iron
(CC) Image: John R. Brews
Magnetic flux density vs. magnetic field in steel and iron
Widlar current source
Widlar current source using bipolar transistors
(CC) Image: John R. Brews
Widlar current source using bipolar transistors
Small-signal circuit for finding output resistance of the Widlar source
(CC) Image: John R. Brews
Small-signal circuit for finding output resistance of the Widlar source
Design trade-off between output resistance and output current in Widlar source
(CC) Image: John R. Brews
Design trade-off between output resistance and output current in Widlar source
Forces
Force and its equivalent force and couple
(CC) Image: John R. Brews
Force and its equivalent force and couple
Centripetal force FC upon an object held in circular motion by a string of length R. The string is under tension FT, as shown separately to the left.
(PD) Image: John R. Brews
Centripetal force FC upon an object held in circular motion by a string of length R. The string is under tension FT, as shown separately to the left.
Upper panel: Ball on a banked circular track moving with constant speed v; Lower panel: Forces on the ball.
(PD) Image: John R. Brews
Upper panel: Ball on a banked circular track moving with constant speed v; Lower panel: Forces on the ball.
Polar unit vectors at two times t and t + dt for a particle with trajectory r ( t ); on the left the unit vectors uρ and uθ at the two times are moved so their tails all meet, and are shown to trace an arc of a unit radius circle.
(PD) Image: John R. Brews
Polar unit vectors at two times t and t + dt for a particle with trajectory r ( t ); on the left the unit vectors uρ and uθ at the two times are moved so their tails all meet, and are shown to trace an arc of a unit radius circle.
Local coordinate system for planar motion on a curve.
(PD) Image: John R. Brews
Local coordinate system for planar motion on a curve.
Exploded view of rotating spheres in an inertial frame of reference showing the centripetal forces on the spheres provided by the tension in a rope tying them together.
(PD) Image: John R. Brews
Exploded view of rotating spheres in an inertial frame of reference showing the centripetal forces on the spheres provided by the tension in a rope tying them together.
Rotating spheres subject to centrifugal (outward) force in a co-rotating frame in addition to the (inward) tension from the rope.
(PD) Image: John R. Brews
Rotating spheres subject to centrifugal (outward) force in a co-rotating frame in addition to the (inward) tension from the rope.
The "whirling table". The rod is made to rotate about the axis and (from the bead's viewpoint) the centrifugal force acting on the sliding bead is balanced by the weight attached by a cord over two pulleys.
(PD) Image: John R. Brews
The "whirling table". The rod is made to rotate about the axis and (from the bead's viewpoint) the centrifugal force acting on the sliding bead is balanced by the weight attached by a cord over two pulleys.
Force diagram for an element of water surface in co-rotating frame.
(PD) Image: John R. Brews
Force diagram for an element of water surface in co-rotating frame.
An object located at xA in inertial frame A is located at location xB in accelerating frame B.
(PD) Image: John R. Brews
An object located at xA in inertial frame A is located at location xB in accelerating frame B.
An orbiting but fixed orientation coordinate system B, shown at three different times.
(PD) Image: John R. Brews
An orbiting but fixed orientation coordinate system B, shown at three different times.
An orbiting coordinate system B in which unit vectors uj, j = 1, 2, 3 rotate to face the rotational axis.
(PD) Image: John R. Brews
An orbiting coordinate system B in which unit vectors uj, j = 1, 2, 3 rotate to face the rotational axis.
Crossing a rotating carousel walking at constant speed, a spiral is traced out in the inertial frame, while a simple straight radial path is seen in the frame of the carousel.
Crossing a rotating carousel walking at constant speed, a spiral is traced out in the inertial frame, while a simple straight radial path is seen in the frame of the carousel.
Rotating shaft unbalanced by two identical attached weights.
(PD) Image: John R. Brews
Rotating shaft unbalanced by two identical attached weights.
An ellipsoid showing its axes
(PD) Image: John R. Brews
An ellipsoid showing its axes
While the pendulum P swings in a fixed plane about its hanger at H, the planes of the Earth observer rotate.
(PD) Image: John R. Brews
While the pendulum P swings in a fixed plane about its hanger at H, the planes of the Earth observer rotate.
Electromagnetism
Electric motor using a current loop in a magnetic flux density, labeled B
(CC) Image: John R. Brews
Electric motor using a current loop in a magnetic flux density, labeled B
Devices
Cross section of MOS capacitor showing charge layers
(PD) Image: John R. Brews
Cross section of MOS capacitor showing charge layers
Three types of MOS capacitance vs. voltage curves. VTH = threshold, VFB = flatbands 
(PD) Image: John R. Brews
Three types of MOS capacitance vs. voltage curves. VTH = threshold, VFB = flatbands 
Small-signal equivalent circuit of the MOS capacitor in inversion with a single trap level
(PD) Image: John R. Brews
Small-signal equivalent circuit of the MOS capacitor in inversion with a single trap level
A modern MOSFET
(PD) Image: John R. Brews
A modern MOSFET
A power MOSFET; source and body share a contact.
(PD) Image: John R. Brews
A power MOSFET; source and body share a contact.
Calculated density of states for crystalline silicon.
(CC) Image: John R. Brews
Calculated density of states for crystalline silicon.
Field effect: At a gate voltage above threshold a surface inversion layer of electrons forms at a semiconductor surface.
(CC) Image: John R. Brews
Field effect: At a gate voltage above threshold a surface inversion layer of electrons forms at a semiconductor surface.
Occupancy comparison between n-type, intrinsic and p-type semiconductors.
(PD) Image: John R. Brews
Occupancy comparison between n-type, intrinsic and p-type semiconductors.
Nonideal pn-diode current-voltage characteristics
(PD) Image: John R. Brews
Nonideal pn-diode current-voltage characteristics
Band-bending diagram for pn-junction diode at zero applied voltage
(PD) Image: John R. Brews
Band-bending diagram for pn-junction diode at zero applied voltage
Band-bending for pn-diode in reverse bias
(PD) Image: John R. Brews
Band-bending for pn-diode in reverse bias
Quasi-Fermi levels in reverse-biased pn-junction diode
(PD) Image: John R. Brews
Quasi-Fermi levels in reverse-biased pn-junction diode
Band-bending diagram for pn-diode in forward bias
(PD) Image: John R. Brews
Band-bending diagram for pn-diode in forward bias
Fermi occupancy function vs. energy departure from Fermi level in volts for three temperatures
(PD) Image: John R. Brews
Fermi occupancy function vs. energy departure from Fermi level in volts for three temperatures
Fermi surface in k-space for a nearly filled band in the face-centered cubic lattice
(PD) Image: John R. Brews
Fermi surface in k-space for a nearly filled band in the face-centered cubic lattice
A constant energy surface in the silicon conduction band consists of six ellipsoids.
(PD) Image: John R. Brews
A constant energy surface in the silicon conduction band consists of six ellipsoids.
Planar Schottky diode with n+-guard rings and tapered oxide.
(PD) Image: John R. Brews
Planar Schottky diode with n+-guard rings and tapered oxide.
Comparison of Schottky and pn-diode current voltage curves.
(PD) Image: John R. Brews
Comparison of Schottky and pn-diode current voltage curves.
Schottky barrier formation on p-type semiconductor. Energies are in eV.
(PD) Image: John R. Brews
Schottky barrier formation on p-type semiconductor. Energies are in eV.
Schottky diode under forward bias VF.
(PD) Image: John R. Brews
Schottky diode under forward bias VF.
Schottky diode under reverse bias VR.
(PD) Image: John R. Brews
Schottky diode under reverse bias VR.
Critical electric field for breakdown versus bandgap energy in several materials.
(PD) Image: John R. Brews
Critical electric field for breakdown versus bandgap energy in several materials.
Schottky barrier height vs. metal electronegativity for some selected metals on n-type silicon.
(PD) Image: John R. Brews
Schottky barrier height vs. metal electronegativity for some selected metals on n-type silicon.
Vestibular system
When the semicircular canal stops rotating, inertia causes the cupula to register a false rotation in the opposite sense.
(PD) Image: John R. Brews
When the semicircular canal stops rotating, inertia causes the cupula to register a false rotation in the opposite sense.
Top: The semicircular canals with head erect. Bottom: the canals with head tipped forward.
(PD) Image: John R. Brews
Top: The semicircular canals with head erect. Bottom: the canals with head tipped forward.