Showing papers on "Responsivity published in 1975"

Submillimeter detection using a Schottky diode with a long‐wire antenna

Abstract: A Schottky diode originally made for use as a detector and a mixer in the millimeter‐waveglength region has been used as a room‐temperature fast detector in the submillimeter‐wavelength region. A voltage responsivity of 2 V/W and an NEP of 1×10−7 W/Hz1/2 at 337 μm were obtained by using high‐gain long‐wire‐antenna coupling. The experimental and theoretical responses of the antenna structure are compared.

Infrared detector arrays by new technologies

Abstract: Techniques for fabricating single-crystal and thin-film detector arrays for infrared remote sensing have been developed in the last few years in most advanced solid-state laboratories. Arrays of photovoltaic devices have been prepared by liquid-phase epitaxy and vapor transport, and by the formation of metal-semiconductor structures and by proton bombardment. A great improvement in infrared thin-film devices was also achieved in the last few years by the vacuum deposition of epitaxial and polycrystalline films. A new technique to obtain high-quality middle-infrared detector arrays has been developed by the use of RF sputtering. Ternary chalcogenide layers with interesting properties for fabricating multi-element detector arrays have been obtained by an RF multicathode sputtering. Pb x Sn 1-x Te films, with a composition-dependent energy gap, have been deposited employing an RF multicathode sputtering system capable of simultaneous and sequential sputtering at different rates from three different targets. Single-crystal and polycrystalline films have been investigated in the course of developing bidimensional detector arrays. Heteroepitaxial films of Pb x Sn 1-x Te at substrate temperatures lower than that needed in conventional evaporation techniques have been obtained using NaCl and BaF 2 substrates. Moreover, epitaxial films with electrical properties close to the best single-crystal values have been obtained on germanium substrates. Using the cosputtering technique, it has been possible to obtain n-type and p-type layers just by controlling the quantity of excess metal or tellurium, respectively. Polycrystalline photoconductive detectors deposited by RF sputtering have shown responsivity and detectivity values higher than previously reported. Exceptionally high responsivity values have been obtained-better than 106V/W in PbTe films and 480 V/W in Pb 0.85 Sn 0.15 Te films. Peak detectivities D λ *(4.5 µ, 800, 1) > 8 × 1010cm ċ Hz1/2/W in PbTe detectors and D λ *(8.5 µ, 800, 1) > 109cm ċ Hz1/2/W in Pb x Sn 1-x Te detectors have been measured with a 2π-steradian field of view at an operating temperature of 77 K. These results are particularly important for the films deposited on germanium and silicon substrates, because of the easy incorporation of electronic readout elements into a completely integrated thermal vision system. Performance data are presented for blackbody and spectral detectivity, impedance, noise, and time constants. Distributions of measured data for linear staggered detector arrays are reported.

Photodetector system for determination of the wavelength of incident radiation

Abstract: A photodetector system is used to resolve the wavelength of an unknown line source in a broad spectral range or to determine the temperature of blackbody or other broad band sources. The photodetector system includes two photodetectors having the same band gap but different thicknesses. The thicker of the two photodetectors receives radiation transmitted by the thinner photodetector. Because responsivity and quantum efficiency are influenced by detector thickness, a signal indicative of the wavelength or temperature is produced by taking the ratio of the signals from the two photodetectors.

Experimental characterization of gold-doped infrared-sensing MOSFET's

Abstract: The operation of a new type of infrared photon detector is described. This device is a gold-doped n-channel MOSFET that employs impurity photoionization to modulate its drain-to-source conductance. A simple mathematical model is developed whereby the infrared-sensing MOSFET (IRFET) can be analyzed, and experimental results that verify the model are provided. The near-infrared, i.e., wavelengths from 1.38 to 3.54 µm, response of gold impurity centers in the space-charge region behind the strong surface inversion layer of a MOSFET is shown to correspond to the characteristics observed previously by other authors for the gold centers in bulk silicon. A static read-only memory capability and high responsivity, typically 4 mW/µJ, are the most significant IRFET characteristics. Applications in large-scale-integrated imaging arrays are anticipated.

Absolute fast neutral beam flux measurements using a pyroelectric detector

Abstract: An inexpensive, sensitive pyroelectric bolometer for use as a fast neutral beam detector is described. Experimentally determined responsivity and noise equivalent power are presented, and are shown to agree with theoretical predictions. The detector has been used to measure the power absorption coefficient and the secondary electron ejection coefficients for 150 eV to 10 keV hydrogen and helium atoms impinging on a silver surface.

Integrated grating‐type Schottky‐barrier photodetector with optical channel waveguide

Abstract: A grating‐type Schottky‐barrier photodetector has been incorporated within an optical channel waveguide. Silicon is used as the base material for future integration of optical and electronic components. The fabrication processes are simple and completely compatible with the standard silicon planar technology. Estimated responsivity of the detector is 0.33 μA/μW at a wavelength of 0.6328 μm with nanosecond response time.

Radiation detection by coherent Josephson phenomena in agglomerated tin films

Abstract: We have previously reported radiant energy detection by superconducting thin films in both a thermal (or bolometer) mode and a current mode. We now report evidence that at least some current-mode detection is due to Josephson behavior associated with agglomeration in tin films. The temperature dependence of the critical current agrees with results for Dayem bridges, and we observe microwave-induced steps in the current-voltage characteristics which have the proper dependence on frequency and power. At a constant film resistance the current-mode responsivity shows structure (dips) in its dependence on bias current which shifts with microwave frequency in agreement with the Josephson theory. The films appear to behave like an array of weak links in the "correlated" state as observed by Clark and explained by him and Tilley.

Photometer calibration problem for extended astronomical sources

Abstract: Analysis of calibration tests for the Skylab experimental T027 photometer is used to show that if an instrument is focused at infinity, the uniform extended calibration source should be positioned at distances at least equal to the hyperfocal distance and should be large enough to fill the field of view. It is noted that the field depth can be increased by focusing the optical system at the hyperfocal distance and that this method of focusing reduces the needed diameter of the calibration source to half that of a system focused at infinity. Other calibration methods discussed includes determining the radiance responsivity distance and extrapolating the curve to larger distances as well as extensive mapping of the spatial response combined with the irradiance responsivity to obtain the radiance responsivity.

High power CO2 laser energy detector

Abstract: A CO2 laser energy detector is described which uses the pressure rise generated in a vaccum cell by gaseous infrared absorption to provide linear energy detection over many decades, good responsivity, wide aperture, and in−line beam monitoring. Nonadiabatic pressure measurements resulting when the beam size is less than the cell aperture are discussed.

A wide bandwidth detection and display system for use with TEA CO2 lasers

Abstract: A photoconductive detector based on intravalence band transitions in p−type germanium is described. The detector responsivity is sufficient to drive a travelling−wave oscilloscope (Tektronix 519) without amplification, and consequently has an over−all bandwidth sufficient to display 300−ps−duration pulses from a mode−locked TEA CO2 laser.

Germanium detector for measuring power of λ =10.6 μ radiation

Abstract: An experimental study was made of the reaction of a detector, utilizing the photon drag effect, to high-power (500 kW) CO2 laser pulses. The responsivity (1×10–7 V/W) was determined and the power at which a spark appeared on the surface of germanium (7×106 W/cm2) was measured. This spark produced an additional voltage pulse which was superimposed on the useful signal.

Detection of 890 GHz radiation with a metal-oxide-metal diode

Abstract: An investigation was made of the behavior of a W–Co point-contact diode in video and heterodyne detection of 890 GHz radiation. It was found that additional oxidation of the substrate could increase the responsivity of the diode by a factor in excess of 2.