Texas Instruments Corporation

Mark A Reed

Gary A Frazier

Robert T Bate

William R Frensley

Homer B Klonis

Jhang W Lee

Arlene Y Yeh

An electronic device (10) such as that of the micromechanical type having a time-released source of a passivant (20). This source (20) is preferably comprised of an impregnated molecular sieve/binder combination, preferably being a polymer. The passivant may be PFDA. The time-released passivant source continuously over the life of the device reduces any tendency of engaged or contacting elements to stick, adhere, or otherwise resist separation. The present invention finds particular use in spatial light modulators of the DMD type. The molecular sieve/binder can also include getter/desiccant source, such as a non-evaporable getter to remove moisture from the hermetically sealed electronic device.

Micromechanical device including time-release passivant

Optically pumped coupled quantum well devices are disclosed. The devices store bits as carrier packets in depressions in the conduction and/or valence band(s) of a single crystal; the band between the depressions is sloped in a common direction which provides unidirectionality. The carrier packets are shifted from depression to depression by optically exciting the carriers and relying on the arrangement of depressions and band slopes; the excitation is conveniently performed by laser illumination. The depressions may be sufficiently small to discretize the energy levels and thereby permit the partitioning of the depressions into groups with each group having depressions of substantially the same energy level structure. The carriers in depressions of one group can then be selectively excited by illumination with a laser or narrow band monochromatic incoherent light source tuned to the energy level structure; this allows multiphase operation of the shifting function.

Optically pumped quantum coupled devices

A tunneling device (50) with the emitter (62) to collector (58) current transported by resonant tunneling through a quantum well (52) and controlled by carriers injected into the well (52) from a base (60) is disclosed. The injected carriers occupy a first energy level in the well (52) and the resonant tunneling is thorough a second energy level in the well (52) thereby separating the controlled carriers from the controlling carriers. Another Three-terminal tunneling devices using three different bandgap semiconductor materials to segregate controlling carriers from controlled carriers are disclosed. Preferred embodiments include narrow bandgap quantum wells and medium bandgap emitters so that narrow bandgap bases may inject and withdraw controlling electrons to the well by tunneling with the controlled electron current tunneling through a higher energy level in the well or so that medium bandgap bases may control holes in the well with only a small forward bias on the emitter-base junction and thereby control electrons tunneling through the well from emitter to collector.

Three terminal tunneling device and method

A new kind of electronic logic circuit, wherein potential wells (e.g. islands of GaAs in an AlGaAs lattice) are made small enough that the energy levels of carriers within the wells are discretely quantized. This means that, when the bias between the wells is adjusted to align energy levels of the two wells, tunneling will occur very rapidly, whereas when the energy levels are not aligned, tunneling will be greatly reduced. In particular, the wells are optimized to have sharp enough resonant tunneling peaks that the change in potential caused by the difference between the number of carriers stored between two adjacent tunnel wells is itself enough to permit or preclude resonant tunneling. Thus, a tremendous variety of logic functions, including all primitive Boolean functions can be embodied in this logic.

Quantum-well logic using self-generated potentials

A tunneling device (50) with the emitter (62) to collector (58) current transported by resonant tunneling through a quantum well (52) and controlled by carriers injected into the well (52) from a base (60) is disclosed. The injected carriers occupy a first energy level in the well (52) and the resonant tunneling is thorough a second energy level in the well (52) thereby separating the controlled carriers from the controlling carriers. Three-terminal tunneling devices using three different bandgap semiconductor materials to segregate controlling carriers from controlled carriers are disclosed. Preferred embodiments include narrow bandgap quantum wells and medium bandgap emitters so that narrow bandgap bases may inject and withdraw controlling electrons to the well by tunneling with the controlled electron current tunneling through a higher energy level in the well or so that medium bandgap bases may control holes in the well with only a small forward bias on the emitter-base junction and thereby control electrons tunneling through the well from emitter to collector.

A three-terminal quantum well device, which functions somewhat analogously to an MOS transistor. That is, the three terminals of the device can generally be considered as source, gate, and drain. An output contact is connected by tunneling to a number of parallel chains of quantum wells, each well being small enough that the energy levels in the well are quantized discretely. In each of these chains of wells, the second well is coupled to a common second conductor, and the first well is electronically coupled to a common first conductor.

Three-terminal quantum device

A resonant tunneling diode (30) with anode (40) and cathode (32) separated by binary short-period superlattice tunneling barriers (34,38) with a quantum well (36) between is disclosed. Enhancement and depletion mode diodes are disclosed.

Binary superlattice tunneling device and method

Quantum-coupled devices, wherein at least two closely adjacent potential wells, (e.g. islands of GaAs in an AlGaAs lattice) are made small enough that the energy levels of carriers within the wells are discretely quantized. This means that, when the bias between the wells is adjusted to align energy levels of the two wells, tunneling will occur very rapidly, whereas when energy levels are not aligned, tunneling will be greatly reduced. To provide output coupling from these quantum-well devices to macroscopic currents, the output from the quantum-well devices is injected into localized states close to an extremely small metal line (e.g. 200 Angstroms square in section). These trapped charged perturb the resistance of a metal line significantly, so that a conventional sense amplifier can be used for differential sensing between two such narrow metal lines, to provide macroscopic outputs.

Quantum device output switch

The present invention teaches a process for fabrication of quantum-well devices, in which the quantum-wells are configured as small islands of GaAs in an AlGaAs matrix. Typically these islands are roughly cubic, with dimensions of about 100 Angstroms per side. To fabricate these, an n- on n+ epitaxial GaAs structure is grown, and then is etched to an e-beam defined patterned twice, and AlGaAs is epitaxially regrown each time. This defines the quantum wells of GaAs in the AlGaAs matrix, and output contacts are then easily formed.

Process for fabricating quantum-well devices

A light modulator and a high speed spatial light modulator (230) with each pixel (231) made of stacked quarter wavelength layers (232, 234) of heterogeneous material. Each layer (232, 234) is composed of periodic quantum well structures whose optical constants can be strongly perturbed by bias on control electrodes (240, 242). The control electrodes (240, 242) act to either remove light absorbing electrons from the layer or to inject them into each layer. The effect is to produce either a highly relecting mirror or a highly absorbing structure. The spatial light modulator (230) is compatible with semiconductor processing technology. Also, a modulator invoking the Burstein effect in the form of a stack of p-n diodes is disclosed.

Spatial light modulator

The present invention teaches a process for fabrication of quantum-well devices, in which the quantum-wells are configured as small islands of GaAs in an AlGaAs matrix. Typically these islands are roughly cubic, with dimensions of about 100 Angstroms per side. To fabricate these, an n- on n+ epitaxial GaAs structure is grown, and then is etched to an e-beam defined patterned twice, and AlGaAs is epitaxially regrown each time. This defines the quantum wells of GaAs in an AlGaAs matrix, and output contacts are then easily formed.

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Dallas, TX, United States of America

Mark A Reed