Abstract: Imaging arrays comprising at least two different imaging pixel types are described. The different imaging pixel types may differ in their light sensitivities and/or light saturation levels. Methods of processing the output signals of the imaging arrays are also described, and may produce images having a greater dynamic range than would result from an imaging array comprising only one of the at least two different imaging pixel types.

Abstract: An improved CMOS pixel with a combination of analog and digital readouts to provide a large pixel dynamic range without compromising low-light performance using a comparator to test the value of an accumulated charge at a series of exponentially increasing exposure times. The test is used to stop the integration of photocurrent once the accumulated analog voltage has reached a predetermined threshold. A one-bit output value of the test is read out of the pixel (digitally) at each of the exponentially increasing exposure periods. At the end of the integration period, the analog value stored on the integration capacitor is read out using conventional CMOS active pixel readout circuits.

Abstract: In accordance with the invention, a photonic device comprises a semiconductor substrate including at least one circuit component comprising a metal silicide layer and an overlying layer including at least one photoresponsive component. The metal silicide layer is disposed between the circuit component and the photoresponsive component to prevent entry into the circuit component of light that penetrates the photoresponsive component. The silicide layer advantageously reflects the light back into the photoresponsive element. In addition, the overlying layer can include one or more reflective layers to reduce entry of oblique light into the photoresponsive component. In an advantageous embodiment, the substrate comprises single-crystal silicon including one or more insulated gate field effect transistors (IGFETs), and/or capacitors, and the photoresponsive element comprises germanium and/or germanium alloy epitaxially grown from seeds on the silicon.

Abstract: Optical imaging structures and methods are disclosed. One structure may be implemented as an imaging pixel having multiple photodetectors. The photodetectors may detect different wavelengths of incident radiation, and may be operated simultaneously or at separate times. An imager may include an imaging array of pixels of the type described. Methods of operating such structures are also described.

Abstract: Imagers, pixels, and methods of using the same are disclosed for imaging in various spectra, such as visible, near infrared (IR), and short wavelength IR (SWIR). The imager may have an imaging array having pixels of different types. The different types of pixels may detect different ranges of wavelengths in the IR, or the SWIR, spectra. The pixels may include a filter which blocks some wavelengths of radiation in the IR spectrum while passing other wavelengths. The filter may be formed of a semiconductor material, and therefore may be easily integrated with a CMOS pixel using conventional CMOS processing techniques.

Abstract: A high-speed optical communications cell is integrated at the interior of a two-dimensional imaging array. The combined receiver and imager carries out both photodetection (converting photons to electrons) and circuit functions (e.g. amplifying and integrating the signals from the photodetectors). The high-speed receiver cell comprises a photodetector and a high-speed amplification circuit, providing an electrical output which can follow a rapidly varying optical signal falling on the photodetector. The imaging array comprises an array of photodetectors and readout circuits, providing an electrical representation of the variation of light with position across the receiver surface. The presence of an imaging array surrounding the communications receiver, and in the same plane as it, allows a single optical path to be used for source acquisition and tracking as well as for data reception.

Abstract: In accordance with the invention, a photonic device comprises a semiconductor substrate including at least one circuit component comprising a metal silicide layer and an overlying layer including at least one photoresponsive component. The metal silicide layer is disposed between the circuit component and the photoresponsive component to prevent entry into the circuit component of light that penetrates the photoresponsive component. The silicide layer advantageously reflects the light back into the photoresponsive element. In addition, the overlying layer can include one or more reflective layers to reduce entry of oblique light into the photoresponsive component. In an advantageous embodiment, the substrate comprises single-crystal silicon including one or more insulated gate field effect transistors (IGFETs), and/or capacitors, and the photoresponsive element comprises germanium and/or germanium alloy epitaxially grown from seeds on the silicon.

Abstract: MOS imaging pixels are described. The MOS imaging pixels may comprise bootstrapped source followers, having their bodies connected to their sources. The source followers of the MOS imaging pixels may be used to buffer a signal indicative of an amount of radiation incident on the pixel. MOS imagers are also described, which may comprise one or more MOS imaging pixels of the type described.

Abstract: A monolithically integrated electronic circuit using two different semiconductor layers which are separated by a dielectric layer. Transistors formed in the upper semiconductor layer are connected to transistors formed in the lower semiconductor layer via conventional wiring. Preferably, one layer of transistors is of one polarity, N-type or P-type, while the second layer of transistors is of the opposite polarity.

Abstract: In accordance with the invention, an improved image sensor comprises an array of germanium photosensitive elements integrated with a silicon substrate and integrated with silicon readout circuits. The silicon transistors are formed first on a silicon substrate, using well known silicon wafer fabrication techniques. The germanium elements are subsequently formed overlying the silicon by epitaxial growth. The germanium elements are advantageously grown within surface openings of a dielectric cladding. Wafer fabrication techniques are applied to the elements to form isolated germanium photodiodes. Since temperatures needed for germanium processing are lower than those for silicon processing, the formation of the germanium devices need not affect the previously formed silicon devices. Insulating and metallic layers are then deposited and patterned to interconnect the silicon devices and to connect the germanium devices to the silicon circuits.

Abstract: In accordance with the invention, an improved image sensor comprises an array of germanium photosensitive elements integrated with a silicon substrate and integrated with silicon readout circuits. The silicon transistors are formed first on a silicon substrate, using well known silicon wafer fabrication techniques. The germanium elements are subsequently formed overlying the silicon by epitaxial growth. The germanium elements are advantageously grown within surface openings of a dielectric cladding. Wafer fabrication techniques are applied to the elements to form isolated germanium photodiodes. Since temperatures needed for germanium processing are lower than those for silicon processing, the formation of the germanium devices need not affect the previously formed silicon devices. Insulating and metallic layers are then deposited and patterned to interconnect the silicon devices and to connect the germanium devices to the silicon circuits.

Abstract: A photodetector is formed from a body of semiconductor material substantially surrounded by dielectric surfaces. A passivation process is applied to at least one surface to reduce the rate of carrier generation and recombination on that surface. Photocurrent is read out from at least one electrical contact, which is formed on a doped region whose surface lies entirely on a passivated surface. Unwanted leakage current from un-passivated surfaces is reduced through one of the following methods. (a) The un-passivated surface is separated from the photo-collecting contact by at least two junctions (b) The un-passivated surface is doped to a very high level, at least equal to the conduction band or valence band density of states of the semiconductor (c) An accumulation or inversion layer is formed on the un-passivated surface by the application of an electric field. Electrical contacts are made to all doped regions, and bias is applied so that a reverse bias is maintained across all junctions.

Abstract: An improved CMOS pixel with a combination of analog and digital readouts to provide a large pixel dynamic range without compromising low-light performance using a comparator to test the value of an accumulated charge at a series of exponentially increasing exposure times. The test is used to stop the integration of photocurrent once the accumulated analog voltage has reached a predetermined threshold. A one-bit output value of the test is read out of the pixel (digitally) at each of the exponentially increasing exposure periods. At the end of the integration period, the analog value stored on the integration capacitor is read out using conventional CMOS active pixel readout circuits.

Abstract: A photodetector is formed from a body of semiconductor material substantially surrounded by dielectric surfaces. A passivation process is applied to at least one surface to reduce the rate of carrier generation and recombination on that surface. Photocurrent is read out from at least one electrical contact, which is formed on a doped region whose surface lies entirely on a passivated surface. Unwanted leakage current from un-passivated surfaces is reduced through one of the following methods. (a) The un-passivated surface is separated from the photo-collecting contact by at least two junctions (b) The un-passivated surface is doped to a very high level, at least equal to the conduction band or valence band density of states of the semiconductor (c) An accumulation or inversion layer is formed on the un-passivated surface by the application of an electric field. Electrical contacts are made to all doped regions, and bias is applied so that a reverse bias is maintained across all junctions.