California Institute of Technology

The United States of America As Represented by the Administrator of the

University of Southern California

John K Liu

Sarath D Gunapala

Sumith V Bandara

Daniel W Wilson

True-Lon Lin

David Z Ting

Bruce R Hancock

Frank J Grunthaner

Jin S Park

Mani Sundaram

Axel Scherer

William J Parrish

Emil Paskalev Kartalov

Clive R Taylor

Sir B Rafol

Jason M Mumolo

Multi-valve autoregulatory microfluidic devices and methods are described. The described devices and methods offer improved performance and new means of tuning autoregulatory effects in microfluidic devices.

Multi-valve microfluidic devices and methods

A quantum well infrared photodetector (QWIP) focal plane array having structures, each structure having stacked layers of quantum wells and a reflective grating to provide polarization sensitivity. The reflective grating is etched to provide electrical contacts for individual pixels. The reflective gratings comprise grooves, where the grooves for a particular structure run in a particular direction to provide polarization sensitivity. Each structure may comprise groups of quantum well layers, each group sensitive to a particular frequency band. By shorting out unwanted quantum well layers, and by forming the reflective gratings to come into contact with the quantum well layers having a particular frequency band sensitivity, the pixels in the QWIP focal plane array may provide frequency and polarization information.

Polarization-sensitive quantum well infrared photodetector focal plane array

Quantum-well sensors having an array of spatially separated quantum-well columns formed on a substrate. A grating can be formed increase the coupling efficiency.

Quantum well sensor having spatially separated sensing columns

Devices and techniques for coupling radiation to intraband quantum-well semiconductor sensors that are insensitive to the wavelength of the coupled radiation. At least one reflective surface is implemented in the quantum-well region to direct incident radiation towards the quantum-well layers.

Wavelength-insensitive radiation coupling for multi-quantum well sensor based on intersubband absorption

An Al Ga As/GaAs/Al Ga As quantum well exhibiting a bound-to-quasibound intersubband absorptive transition is described. The bound-to-quasibound transition exists when the first excited state has the same energy as the &ldquo;top&rdquo; (i.e., the upper-most energy barrier) of the quantum well. The energy barrier for thermionic emission is thus equal to the energy required for intersubband absorption. Increasing the energy barrier in this way reduces dark current. The amount of photocurrent generated by the quantum well is maintained at a high level.

Infrared radiation-detecting device

Device designs and techniques for reducing the dark current in quantum-well detectors.

Multi-quantum-well detector for low-background applications

Device designs and techniques for forming multiple-band quantum-well detectors.

Multi-quantum-well infrared sensor array in spatially-separated multi-band configuration

A three-color QWIP focal plane array is based on a GaAs/AlGaAs material system. Three-color QWIPs enable target recognition and discriminating systems to precisely obtain the temperature of two objects in the presence of a third unknown parameter. The QWIPs are designed to reduce the normal reflection over a significant wavelength range. One aspect of the present invention involves two photon absorptions per transition in a double quantum well structure which is different from typical QWIP structures. This design is expected to significantly reduce the dark current as a result of higher thermionic barriers and therefore allow the devices to operate at elevated temperatures. The device is expected to be fabricate using a GaAs/Al Ga As material system on a semi-insulating GaAs substrate by Molecular Beam Epitacy (MBE).

Three color quantum well infrared photodetector focal plane array

Techniques for coupling radiation into a quantum-well detector by using a two-dimensional array of grating cells to form at least three different grating directions to provide efficient coupling.

Multi-directional radiation coupling in quantum-well infrared photodetectors

Slotted quantum well sensor

An Al,Ga,As/GaAs/Al,Ga,As quantum well exhibiting a bound-to-quasibound intersubband absorptive transition is described. The bound-to-quasibound transition exists when the first excited state has the same energy as the &ldquo;top&rdquo; (i.e., the upper-most energy barrier) of the quantum well. The energy barrier for thermionic emission is thus equal to the energy required for intersubband absorption. Increasing the energy barrier in this way reduces dark current. The amount of photocurrent generated by the quantum well is maintained at a high level.

Quantum-well sensing arrays for detecting radiation with two or more wavelengths. Each pixel includes at least two different quantum-well sensing stacks that are biased at a common voltage.

Dual-band quantum-well infrared sensing array having commonly biased contact layers

For the growth of strain-layer materials and high quality single and multiple quantum wells, the instantaneous control of growth front stoichiometry is critical. The process of the invention adjusts the offset or phase of MBE control shutters to program the instantaneous arrival or flux rate of In and As.sub.4 reactants to grow InAs. The interrupted growth of first In, then As.sub.4, is also a key feature.

Growth of III-V films by control of MBE growth front stoichiometry

III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group II and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation to low temperature, and to permit the film to relax to equilibrium. The method of the invention 1) minimizes starting step density on sample surface; 2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 mono-layers at a time); 3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and 4) uses time-resolved RHEED to achieve aspects (1)-14 (3).

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Pasadena, CA, United States of America

John K Liu