Santa Barbara Research Center

Ichiro Kasai

Herbert L Hettich

Stephen L Lawrence

Richard J Joyce

Eric Frank Schulte

John R Toman

Joseph P Rosbeck

Bonnie A Baumgratz

Charley B Burgett

Roderic L Osgood

James E Randolph

Richard M Wallach

Michael D Warfield

Michael E Boyd

The light receiving or back-side surface (22) of an indium antimonide (InSb) photodetector device (10) substrate (12) is cleaned to remove all native oxides of indium and antimony therefrom. A passivation layer (26) is then formed on the surface (22) of a material such as silicon dioxide, silicon suboxide and/or silicon nitride which does not react with InSb to form a structure which would have carrier traps therein and cause flashing. The device (10) is capable of detecting radiation over a continuous spectral range including the infrared, visible and ultraviolet regions.

Indium antimonide (InSb) photodetector device and structure for

The light receiving or back-side surface (22) of an indium antimonide (InSb) photodetector device (10) substrate (12) is cleaned to remove all oxides of indium and antimony therefrom. Passivation and/or partially visible light blocking layers (26, 28) are then formed thereon of a material which does not react with InSb to form a structure which would have carrier traps therein and cause flashing. The optical cutoff wavelength and thickness of the partially visible light blocking layer (28) are selected to suppress the avalanche effect in the device (10) at visible wavelengths. This enables the device (10) to operate effectively over a wide wavelength range including the visible and infrared bands. The passivation and/or partially visible light blocking layers (26, 28) may be a thin layer of a semiconductor such as germanium, or silicon dioxide and/or silicon nitride followed by a partially visible light blocking silicon layer.

Visible and infrared indium antimonide (INSB) photodetector with

A four-layer, wideband anti-reflection coating (30) is formed on a light-receiving surface (22) of an indium antimonide (InSb) photodetector (10) to enable detection of light at visible as well as infrared wavelengths. The layers (30a,30b,30c,30d) each have an optical thickness of approximately one-quarter wavelength at a reference wavelength of 1.6 microns. The refractive indices of the layers (30a,30b,30c,30d) are stepped down from the surface (22), having values of approximately 3.2/2.6/1.9/1.45 respectively. The second layer (30b) is preferably formed of silicon suboxide (SiO.sub.0&lt;X&lt;1) by electron-beam deposition of silicon in an oxygen backfill to obtain a refractive index between the indices of silicon and silicon monoxide. A thin passivation layer (26) of germanium or silicon nitride is formed on the surface (22) under the anti-reflection coating (30) to inhibit a flashing effect at infrared wavelengths after exposing to the ultraviolet (UV) and/or visible light.

Wideband anti-reflection coating for indium antimonide photodetector

A method is disclosed for passivating infrared detector arrays 50. A wafer 48 of indium antimonide (InSb) is subjected an anodization process while being illuminated by a bright incandescent lamp 66. In one embodiment, the photo-anodized layer 72 is used in an array 50 to passivate implanted diode regions 76,78 on the front side thereof, while employing an antireflective coating 74 on the backside anodized surface 70.

Photo-anodic oxide surface passivation for semiconductors

A detector assembly for reception of infrared radiation is formed as a composite structure of a detector array electrically connected by a set of contacts to a readout clip disposed on a backside of the assembly opposite a front side receiving incident radiation. Individual detectors are formed of layers of P-type and N-type semiconductor material, and are spaced apart from each other and from the readout chip by resilient electrically-insulating polymeric material which supports the detectors in their respective positions while allowing for thermally induced displacement of the detectors from their respective positions. A metallic grid on the front surface of the assembly provides a common electrical connection of the detectors to the readout chip. An antireflective coating may also be placed on the front surface of the assembly.

Reticular detector array

Method and apparatus for testing photodiode arrays using an electron beam. The diodes are charged at successive intervals over the RC time constant curve to develop successively increasing voltages at the ends of succeeding time intervals. Diode voltage and current are measured at the end of each interval and the resulting data are used to develop a current-voltage characteristic for each diode.

Electron-beam probing of photodiodes

A HgCdTe photodiode array for detecting mid-wavelength infrared radiation has a laminated structure consisting of a substrate, a heavily doped wide bandgap buffer layer, and a more lightly doped narrow bandgap base layer. Two sets of a orthogonally disposed U-shaped grooves are etched completely through the base layer and partially through the buffer layer, thereby forming a plurality of mesa-shaped structures. Overlying the portion of base layer contained within each mesa is a capping layer of opposite conductivity. The junction of the base and capping layer within each mesa forms a photodiode. In contact with each capping layer is a metalization area for connection of the underlying diode to a readout device. In contact with the buffer layer is another metalization layer for making a common electrical connection to the array of photodiodes. Overlying the mesa surfaces is a layer of passivation which contains a fixed positive charge. The charge creates an inversion layer within the surface of the base layer exposed along the mesa walls, thereby enlarging the p-n junction of each photodiode. Radiation impinging on a lower surface of the transparent substrate passes through the substrate and into the buffer layer, which is also transparent. Transmitted through the buffer layer, the radiation is absorbed within that portion of the base layer contained within each mesa, resulting in the generation of diode currents.

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Solvang, CA, United States of America

Ichiro Kasai