Abstract: A first piece (22) is bonded to a second piece (24) at a selected location (45) by positioning the first piece (22) and second piece (24) between a pair of bonding tools (36 and 38), with the bonding tools at the selected location (45) of the first piece (22) and the second piece (24) where bonding is to be achieved. The selected location (45) of the first piece (22) and the second piece (24) is pressed between the pair of bonding tools (36 and 38) with an applied force (46), the applied force (46) increasing from zero to a prebonding force (64), being maintained at the prebonding force (64) for a prebonding period (66), changing to a bonding force (60), and thereafter decreasing from the bonding force (60) to zero.

Abstract: A double layer heterojunction array 10 of IR photodiodes has formed within an upper planar surface region of a collector layer 16 a plurality of isolation junctions 20 which are disposed between individual photodiodes. The isolation junctions are formed by a thermally driven process of type-converting the p-type or n-type collector layer to the opposite type of material. This type conversion forms p-n homojunctions at the edges of the isolation junctions which isolate the individual photodiodes one from another. The type-conversion process of the invention provides two isotype junctions which together reflect excess minority charge carriers away from the surface of the device as well as from neighboring photodiodes. One method of the invention discloses the selective annealing of the surface of an n-type collector layer to extract mercury atoms thereby creating mercury vacancies which act as acceptors.

Abstract: A thin film electrical cable 20 is disclosed having a polyimide substrate 46, a layer of titanium 48 on a lower side 50 of the substrate 46, and a plurality of gold conductors 52 on the titanium 48. The thin layers of titanium and gold are preferably sequentially deposited on a clean polyimide film by sputtering. Additional gold is electroplated and separate conductors are delineated. The use of organic adhesive materials to attach the conductors 52 to the substrate 46 is avoided.

Abstract: Photodetectors that produce detectivities close to the theoretical maximum detectivity include an electrically insulating substrate carrying a body of semiconductor material that includes a region of first conductivity type and a region of second conductivity type where the region of first conductivity type overlies and covers the junction with the region of second conductivity type and where the junction between the first and second regions separates minority carriers in the region of second conductivity type from majority carriers in the region of first conductivity type. These photodetectors produce high detectivities where radiation incident on the detectors has wavelengths in the range of about 1 to about 25 microns or more, particularly under low background conditions.

Abstract: An infrared detector assembly (12) of the type used in munitions and night vision systems having an improved focal plane platform (10) construction. In accordance with this invention, the thermally conductive focal plane platform (10) supports a detector array (26) and integrated readout chips (28). The focal plane platform (10) includes relatively thermally non-conductive inserts (38) disposed in cavities (36) positioned generally below each integrated read out chip (28). The inserts insulate the chips (28) during cryogenic cooling of detector array (26). Freeze-out of the chips (28) is thereby inhibited.

Abstract: A method for fabricating a plurality of semiconductor photodetectors and an array of same produced by the method. The method includes a first step of selectively removing semiconductor material to form a channel within a semiconductor material for physically isolating a first photodetector from a second photodetector, the semiconductor material having a characteristic energy bandgap. The method includes a second step of selectively increasing the carrier concentration of the semiconductor material within a bottom region of the channel for preventing minority charge carriers from diffusing under the channel from a region associated with the first photodetector to a region associated with the second photodetector. The step of selectively removing is accomplished by the steps of providing a patterned mask upon the semiconductor material and selectively removing the underlying semiconductor material through an opening within the mask.

Abstract: A semiconductor substrate or other object (32) for vapor deposition is mounted on a susceptor disk (16) which rotates about a vertical axis. Chemical vapor flows downwardly through a passageway (14) onto the object (32). A radial space (14a) is provided between the periphery of the disk (16) and an adjacent inner wall (12a) of the passageway (14). Rotation of the disk (16) urges a portion of the vapor flow (60) to be deflected from the disk (16) and the wall (12a) of the passageway (14) upwardly to cause deleterious recirculation of the vapor above the disk (16). A flow guide (52) disposed in the passageway (14) above the disk (16) has an upstream converging section (52a) which causes the flow (56) of vapor to accelerate, and a downstream diverging section (52b) which causes the accelerated flow (58) to expand downwardly and radially outwardly so as to interact with, and prevent upward movement of the deflected portion of the flow (60) and thereby suppress recirculation of the vapor.

Abstract: Object detection apparatus (40) inlcudes a transmitter assembly (44) and a receiver assembly (10). The receiver assembly includes a receiver element (12) having an input aperture (16) for receiving electromagnetic radiation reflecting from an object. The receiver element further includes an output aperture (24) and a curved surface (22) disposed relative to the input aperture for reflecting substantially all electromagnetic radiation (A,B,C) reflecting from an object at a range in excess of a range of interest, to the output aperture. A first radiation detector (14) is disposed at the output aperture for receiving the object radiation reflected thereto and for generating a first electrical signal. A second radiation detector (30) is disposed at a location upon the receiver assembly for receiving object radiation reflected thereto that reflects from an object at a range that is within the range of interest.

Abstract: Methods of fabricating a two-color infrared detector array, and an array of same fabricated by the methods. There is disclosed (a) selectively forming a plurality of first regions upon or within a surface of a substrate, the first regions being comprised of a first semiconductor material having a first type of electrical conductivity and a significant responsivity to wavelengths within a first spectral band. A second step (b) forms a substantially continuous layer comprised of a second semiconductor material over the surface of the substrate and over the plurality of first regions, the layer being comprised of semiconductor material having a second type of electrical conductivity for forming a plurality of first heterojunctions with the first regions. A third step (c) selectively forms a plurality of second regions upon the layer, individual ones of which are in registration with a corresponding one of the first regions.

Abstract: Method and apparatus for performing a TDI function with a plurality of electrical signals. A first step of the method stores, during individual ones of a first plurality of consecutive time intervals, a sample of a first electrical signal. A second step of the method equilibrates, during individual ones of a second, subsequent plurality of time intervals, one of the stored samples with a stored sample of a second electrical signal. Subsequent to each of the steps of equilibrating, an electrical signal is outputted that has a magnitude expressive of the equilibrated stored samples. The equilibration is achieved by shorting storage capacitors (C.sub.1, C.sub.2, C.sub.3) together to effectively sum coherent signals and incoherent noise. The charge sum is stored on a capacitance that is effectively doubled from either detector channel operating individually.

Abstract: The range (R) to a target (12) is precisely determined by controlling the amplitude of the carrier before modulation using a feedback signal derived from the detected return. The amplitude of the carrier is adjusted (40) so that all return pulses have a constant amplitude. Hence, for any given range, all return pulses cross threshold at the same time, thereby eliminating ranging errors due to phase distortion. The return pulses are threshold detected (54) and converted to a CW signal, which is then down converted. The phase information, which is indicative of target range, is preserved in the down conversion process and is extracted by phase comparison (72) with a reference signal to determine the target range.

Abstract: A VLWIR proximity effect detector 10 includes a substrate 12, a bulk superconducting material 14, a proximity layer 16 which overlies a portion of the bulk superconducting material 14, an insulator layer 17 and a transparent tunnelling electrode 18. Detector electrical contacts 19 are provided on the proximity layer 16 and on the electrode 18. VLWIR, indicated by the arrows, is absorbed in proximity layer 16 and causes a detectable modulation of tunnelling characteristics (current or voltage) between the proximity layer 16 and the electrode 18. The proximity layer has a thickness on the order of a coherence length for the material which comprises the proximity layer. In accordance with the invention it has been determined that a spatially varying energy gap (E.sub.gap) induced in the proximity layer by the adjacent superconducting material results in the proximity layer having a longer cut off wavelength than that of the adjacent bulk superconducting material. The lower value of the induced E.sub.

Abstract: A radiation detector 10 includes a first heterojunction 14A and a second heterojunction 16A electrically coupled together in series between a first electrical contact 18 and a second electrical contact 20. The detector comprises at least a three regions or layers including a first layer 12 having a first type of electrical conductivity, a second layer 14 having a second type of electrical conductivity, and a third layer 16 having the first type of electrical conductivity. The first and second heterojunctions are coupled in series and function electrically as two back-to-back diodes. During use the detector is coupled to a switchable bias source 22 that includes a source of positive bias (+Vb) 22A and a source of negative bias (-Vb) 22B. With +Vb applied across the detector the first heterojunction is in far forward bias and functions as a low resistance conductor, thereby contributing no significant amount of photocurrent to the circuit.

Abstract: An infrared detector assembly (10) of the type used in munition and night vision systems having an RF activated getter (50). Such detector assemblies (10) include a tubular coldfinger (22) surrounded by a vacuum and which supports infrared detector array (26) and related components. In accordance with this invention, RF getter (50) is located remote from detector array (26) and engages an inner wall surface (56) of a metallic dewar housing (14). The RF getter (50) is activated via RF inductive heating directly through the metal dewar housing (14) such that sensitive IR detector components and hermetic braze joints are kept below their critical temperature. As a result, the present invention provides longer vacuum life and greater operational reliability of infrared detector assembly (10).

Abstract: A radiation detector assembly (20) includes a radiation detector (2), a silicon readout device (3) coupled to the radiation detector, and a platform 13 for supporting from a first major surface (13a) the readout device and the radiation detector. A second major surface (13b) includes a boss (14) for coupling, via an active brazing operation, to a cryogenic cooler. The platform is monolithic structure comprised of aluminum nitride (AlN) and eliminates at least one adhesive joint found in the prior art. AlN is selected because of its inherent material properties including a higher thermal diffusivity, relative to typical ceramic materials, for providing a reduced cooldown time of the detector to cryogenic temperatures. AlN also has a 300K- 77K thermal contraction characteristic that closely matches that of the silicon readout device and a high modulus of elasticity, thereby reducing distortion of the readout device thus minimizing stresses on indium bump interconnects.

Abstract: A Frequency Domain Infrared Superconducting Transmission Line (FIRST) detector is comprised of a folded superconducting transmission line (36) interposed between a bottom electrode (32) and a top, radiation absorbing electrode (40). Dielectric layers (34, 38) separate the transmission line from the top and bottom electrodes. An optically induced change in the kinetic inductance of the transmission line shifts the transmission line phase velocity and resonant frequency. The shift in resonant frequency attenuates the propagating wave amplitude proportionally to the product of the transmission line Q and the frequency shift. A stacked pair of such detectors (50), sharing a common ground electrode (60), is disclosed to provide an inherent rejection of noise events due to ionizing radiation such as gamma radiation and package-generated Compton electrons.

Abstract: 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.

Abstract: A semiconductor laser chip having one or more lasing junctions is mounted on one side of a thin sheet of thermally conductive material opposite to a second semiconductor laser chip of the same construction mounted on the opposite side. The thin sheet of material allows the emitting facets of the semiconductor laser chips to be placed in close proximity for coupling into the end of an optical fiber or other use. Made of hardened copper or other suitable material, the thin sheet of material serves as a heat conducting path between the semiconductor laser chips and a heat sink. Different configurations may utilize different shapes for the thin sheet of material; the thin sheet may have parallel opposing sides or opposing sides that are at an angle with respect to one another.

Abstract: Photodetectors that produce detectivities close to the theoretical maximum detectivity include an electrically insulating substrate carrying a body of semiconductor material that includes a region of first conductivity type and a region of second conductivity type where the region of first conductivity type overlies and covers the junction with the region of second conductivity type and where the junction between the first and second regions separates minority carriers in the region of second conductivity type from majority carriers in the region of first conductivity type. These photodetectors produce high detectivities where radiation incident on the detectors has wavelengths in the range of about 1 to about 25 microns or more, particularly under low background conditions.

Abstract: A multilayered radiation detector device (50) including a resonant cavity structure wherein one cavity wall electrode includes a portion of a photovoltaic radiation detector (52). Specifically, a RFM detector has a superconducting transmission line electrode (54) electrically coupled to a high mobility semiconductor layer (58) of the photovoltaic detector. The superconductor transmission line electrode inductance forms, in combinations with a photodetector depletion region capacitance, a series resonant or a parallel resonant circuit. A radiation-induced change in the capacitance results in a change in the circuit resonant frequency and a corresponding variation in the amplitude of an on-resonance RF signal applied to the circuit. In another embodiment the resonant cavity structure includes a gap having a width that is modulated by an amount of absorbed radiation, the radiation-induced change in the distributed cavity capacitance resulting in a change in the cavity resonant frequency.