California Institute of Technology

United States of America As Represented by the Administrator of Nasa

Cory J Hill

Sarath D Gunapala

David Z Ting

Sumith V Bandara

Arezou Khoshakhlagh

Harold Frank Greer

Alexander Soibel

Alexander Seibel

Sumith Y Bandara

Disclosed herein is a method of producing an infrared detector. In certain embodiments, the method includes: forming a planar multi-layer structure including an absorber including a superlattice structure; patterning the planar multi-layer structure; etching the planar multi-layer structure to define a plurality of pixels, the sidewalls of the plurality of pixels includes a sidewall roughness and multiple types of surface oxides; and performing a surface treatment process to the plurality of pixels in order to reduce the sidewall roughness and replace the surface oxides with a chlorinated surface morphology. The surface treatment process may reduce surface current of the infrared detector which may decrease the dark current in the infrared detector.

Atomic layer-based surface treatments for infrared detectors

In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

Digital alloy absorber for photodetectors

Systems and methods of implementing barrier infrared detectors on lattice mismatched substrates are provided. The barrier infrared detector systems combine an active detector structure (e.g., contact/barrier/absorber pairs) with a non-lattice matched substrate through a multi-layered transitional structure that forms a virtual substrate that can be strain balanced with the detector structure. The transitional metamorphic layer may include one or both of at least one graded metamorphic buffer layer or interfacial misfit array (IMF). A further interfacial layer may be interposed within the transitional structure, in some embodiments this interfacial layer includes at least one layer of AlSb.

Barrier infrared detectors on lattice mismatch substrates

A barrier infrared detector with absorber materials having selectable cutoff wavelengths and its method of manufacture is described. A GaInAsSb absorber layer may be grown on a GaSb substrate layer formed by mixing GaSb and InAsSb by an absorber mixing ratio. A GaAlAsSb barrier layer may then be grown on the barrier layer formed by mixing GaSb and AlSbAs by a barrier mixing ratio. The absorber mixing ratio may be selected to adjust a band gap of the absorber layer and thereby determine a cutoff wavelength for the barrier infrared detector. The absorber mixing ratio may vary along an absorber layer growth direction. Various contact layer architectures may be used. In addition, a top contact layer may be isolated into an array of elements electrically isolated as individual functional detectors that may be used in a detector array, imaging array, or focal plane array.

High operating temperature barrier infrared detector with tailorable cutoff wavelength

An infrared detector having a hole barrier region adjacent to one side of an absorber region, an electron barrier region adjacent to the other side of the absorber region, and a semiconductor adjacent to the electron barrier.

Complementary barrier infrared detector (CBIRD)

A superlattice-based infrared absorber and the matching electron-blocking and hole-blocking unipolar barriers, absorbers and barriers with graded band gaps, high-performance infrared detectors, and methods of manufacturing such devices are provided herein. The infrared absorber material is made from a superlattice (periodic structure) where each period consists of two or more layers of InAs, InSb, InSbAs, or InGaAs. The layer widths and alloy compositions are chosen to yield the desired energy band gap, absorption strength, and strain balance for the particular application. Furthermore, the periodicity of the superlattice can be 'chirped' (varied) to create a material with a graded or varying energy band gap. The superlattice based barrier infrared detectors described and demonstrated herein have spectral ranges covering the entire 3-5 micron atmospheric transmission window, excellent dark current characteristics operating at least 150K, high yield, and have the potential for high-operability, high-uniformity focal plane arrays.

Barrier infrared detector

An nBn detector is described where for some embodiments the barrier layer has a concentration gradient, for some embodiments the absorption layer has a concentration gradient, and for some embodiments the absorption layer is a chirped strained layer super lattice. The use of a graded barrier or absorption layer, or the use of a chirped strained layer super lattice for the absorption layer, allows for design of the energy bands so that the valence band may be aligned across the device. Other embodiments are described and claimed.

nBn and pBp infrared detectors with graded barrier layer, graded absorption layer, or chirped strained layer super lattice absorption layer

The present invention is directed to methods of photonic crystal formation, and to methods and apparatus for using such photonic crystals, particularly in conjunction with detector arrays. Photonic crystal parameters and detector array parameters are compared to optimize the selection and orientation of a photonic crystal shape. A photonic crystal is operatively positioned relative to a plurality of light sensors. The light sensors can be separated by a pitch distance and positioned within one half of the pitch distance of an exit surface of the photonic crystals.

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Pasadena, CA, United States of America

Cory J Hill