Showing papers on "Responsivity published in 1984"
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TL;DR: High quality antireflection coatings of laser facets have been achieved using sputtered silicon nitride and similar films were also used to AR coat InGaAs PIN detectors thereby significantly increasing their responsivity.
Abstract: Single-layer antireflection (AR) coating films are used to transform semiconductor injection lasers into different kinds of active device. For example, a laser whose emitting facet reflectivities (one or both) are reduced to zero is transformed into a superluminescent diode or an optical amplifier, respectively. AR coated lasers are also very desirable in various configurations of a laser in an external cavity or as sources for optical fiber sensor applications. High quality antireflection coatings of laser facets have been achieved using sputtered silicon nitride. The emitting facets of InGaAsP lasers at 1.3 and 1.55 μm as well as of AlGaAs lasers at 0.85 μm were coated. The reflectivities achieved were consistently in the 0.01–0.03% range. Similar films were also used to AR coat InGaAs PIN detectors thereby significantly increasing their responsivity.
84 citations
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TL;DR: In this paper, the authors used single-crystal silicon thin films on fused silica to fabricate depletion mode transistors, which achieved an optical responsivity of ≳ 300 A/W of incident visible radiation.
Abstract: Exceptionally high photosensitivity has been obtained in metal‐oxide‐semiconductor field‐effect transistors fabricated in single‐crystal silicon thin films on fused silica. The silicon films were laser crystallized and used to fabricate depletion mode transistors. Operating in pinch‐off these buried‐channel devices display an optical responsivity of ≳ 300 A/W of incident visible radiation. This is some four orders of magnitude greater than that achieved in enhancement mode devices of comparable design and processing. The basic mechanism for the high sensitivity is the spatial separation of photogenerated electrons and holes which results in long carrier lifetimes, as indicated by optical gains >103 and photocurrent decay times of the order of 10 μs.
59 citations
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TL;DR: The responsivity of an infrared bolometer detector is deduced from electrical measurements, even for cases when the temperature sensor has electrical nonlinearities.
Abstract: An analytical method for determining the absorbed energy calibration of an IR bolometer from purely electrical measurements is presented. The technique is targeted at detectors with purely electrical nonlinearities. It is shown that the responsivity can be derived from the I-V plot if the limiting high-frequency impedance is measured. The electrical nonlinearity is then the difference between the impedance and the dc resistance. The model is used for designing a circuit for measuring the relative impedance parameters. The results are applicable to studies of IR sources and the detection of energy pulses with bolometers.
51 citations
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TL;DR: In this article, a GaAs photoconductive mixer was used for detection of high-frequency intensity modulation signals using high frequency intensity modulation (HEM) signals using a low power local oscillator, achieving a flat response for optical modulation frequencies up to 4.5 GHz for down-conversion to a 500-MHz intermediate frequency.
Abstract: Optoelectronic heterodyne detection of high-frequency intensity modulation signals using a GaAs photoconductive mixer is reported. Flat response for optical modulation frequencies up to 4.5 GHz is observed for downconversion to a 500-MHz intermediate frequency using a low power local oscillator. Heterodyne responsivity was enhanced significantly over direct detection with the same photoconductive detector due to improved contact performance under RF bias.
48 citations
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TL;DR: In this paper, a new photoconductor device structure was described utilizing a heterojunction contact which incorporates a higher bandgap HgCdTe alloy between the metal contact and the normal band-gap photoconductor.
Abstract: A new photoconductor device structure is described utilizing a heterojunction contact which incorporates a higher band‐gap HgCdTe alloy between the metal contact and the normal band‐gap photoconductor. A theoretical treatment of the heterojunction contact photoconductor (HCP) device shows that carrier sweepout can be virtually eliminated; the calculations predict elimination of ‘‘saturation’’ of responsivity and a very large increase in responsivity. HCP devices were fabricated; experimental results verified the theory in several ways. A responsivity was measured at 80 K of about 450 000 V/W at 30 V/cm and over 1 500 000 V/W at 125 V/cm.
36 citations
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TL;DR: In this article, a theory of generation-recombination (g−r) noise, responsivity, and detectivity D* in intrinsic photoconductors, including for the first time the effects of recombination at the contacts as a variable parameter, is presented.
Abstract: A theory is presented of generation‐recombination (g‐r) noise, responsivity, and detectivity D* in intrinsic photoconductors, including for the first time the effects of recombination at the contacts as a variable parameter. The contacts are described using a contact recombination velocity. Increasing the blocking at the contacts can significantly increase the responsivity, and also push the detectivity toward the background limited value since blocking contacts increase responsivity and the background contribution to the noise voltage faster than the thermal contribution. Blocking contacts also cause both the responsivity and g‐r noise voltage to roll off at lower frequencies. Numerical calculations are presented for X∼0.2 HgCdTe photoconductors. Blocking contacts are found to increase the range of material parameters which can be used to make detectors. For example, under typical conditions, to reach responsivities of 105 V/W and detectivities of 6×1010 cm(Hz)1/2/W at T=77 °K, blocking contacts can incr...
23 citations
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TL;DR: In this paper, optical absorption has been obtained in thin (∼30 nm) layers of hydrogenated amorphous silicon by depositing films on periodically structured substrates, at the appropriate angle of incidence, light is coupled to a surface wave in the abosrbing "artificial dielectric" region formed by the structured interface.
Abstract: Enhanced optical absorption has been obtained in thin (∼30 nm) layers of hydrogenated amorphous silicon by depositing films on periodically structured substrates. At the appropriate angle of incidence, light is coupled to a surface wave in the abosrbing ‘‘artificial dielectric’’ region formed by the structured interface. This effect is used as the basis of high‐speed metal a‐Si:H metal detectors to overcome the conflicting requirements of high optical absorption and short transit times in thin layers. Peak response as high as 0.16 V is achieved for 50‐pJ incident pulses of picosecond duration. This is comparable to that obtained with much higher mobility crystalline semi‐insulators.
22 citations
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TL;DR: In this paper, a high performance interdigitated Al0.48In0.52As/Ga0.53As heterostructure photoconductive detector for high bit-rate, single-mode telecommunication applications is reported.
Abstract: We report a high performance interdigitated Al0.48In0.52As/Ga0.47In0.53As heterostructure photoconductive detector for high bit‐rate, single‐mode telecommunication applications. The detector shows a rise time of 80 ps, a fall time of 1.2 ns, and a peak responsivity seven times better than that of a pin photodiode. Our study shows that the long fall time is due to a slow minority‐carrier (hole) drift velocity coupled with a two‐dimensional effect. We have also tested the demodulation characteristics of the detector at frequencies as high as 2.7 GHz. Furthermore, we have investigated the noise properties of the detector in the frequency band of 100 MHz–1.1 GHz.
22 citations
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TL;DR: The data are seen as indicating that extremely low values of NEP can be obtained for integration times of 1 sec and that longer integrations continue to improve the SNR at a rate faster than the square root of time when background noise is not present.
Abstract: It is shown how a simple integrating amplifier based on commercially available JFET and MOSFET switches can be used to measure photocurrents from detectors with noise levels as low as 1.6 x 10 to the -18th A/root Hz (10 electrons/sec). A figure shows the basic circuit, along with the waveform at the output. The readout is completely nondestructive; the reset noise does not contribute since sampling of the accumulated charge occurs between resets which are required only when the stored charge has reached a very high level. The storage capacity ranges from 10 to the 6th to 10 to the 9th electrons, depending on detector parameters and linearity requirements. Data taken with an Si:Sb detector operated at 24 microns are presented. The responsivity agrees well with the value obtained by Young et al. (1981) in the transimpedance amplifier circuit. The data are seen as indicating that extremely low values of NEP can be obtained for integration times of 1 sec and that longer integrations continue to improve the SNR at a rate faster than the square root of time when background noise is not present.
17 citations
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TL;DR: In this article, a number of different pointcontact diodes were made by mechanically contacting various metals, semimetals and semiconductors with different metallic whiskers, and tested as frequency mixers and harmonic generators using CO2 and CO lasers.
Abstract: A number of different point-contact diodes were made by mechanically contacting various metals, semimetals and semiconductors with different metallic whiskers. The diodes have been tested as frequency mixers and harmonic generators using CO2 and CO lasers. The results suggest that two mechanisms, electron tunnelling through a potential barrier and another slower process are responsible for the operation of the diodes. Some of the new devices are electrically and mechanically more stable than the commonly used tungsten-nickel diode and show better responsivity.
17 citations
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04 Dec 1984TL;DR: In this paper, an improved electromagnetic radiation sensitive semiconductor device together with a method of making same is disclosed in which surface regions directly beneath the active portion of the electrical contacts are provided with a layer of semiconductor material having a higher bandgap than the radiation sensitive material which repels minority carriers but allows the passage of majority carriers.
Abstract: An improved electromagnetic radiation-sensitive semiconductor device together with a method of making same is disclosed in which surface regions directly beneath the active portion of the electrical contacts are provided with a layer of semiconductor material having a higher bandgap than the radiation sensitive material which repels minority carriers but allows the passage of majority carriers. Because the rate of annihilation of minority carriers at the contact to which they are attracted is reduced, the responsivity of the detector is greatly enhanced.
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01 Jan 1984TL;DR: In this article, a 64-element, pyroelectric infrared detector array, fabricated on a thin-membrane structure by combining ZnO thin-film deposition technology, NMOS planar processing, and anisotropic backside etching of silicon is described.
Abstract: A fully-integrated, 64-element, pyroelectric infrared-detector array, fabricated on a thin-membrane structure by combining ZnO thin-film deposition technology, NMOS planar processing, and anisotropic backside etching of silicon is described. Incident thermal radiation on individual detector elements is sensed by the temperature change in a structure composed of a ZnO pyroelectric capacitor encapsulated in silicon dioxide and supported by a 25 µm-thick silicon membrane. Thai measured black-body responsivity at temperature T=300 K and frequency f=24 Hz is 4.3 × 104VW-1with a corresponding measured detectivity D*=3.1 × 107cm √ HzW-1.
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TL;DR: This monolithic array demonstrates compact broadband matrix switching of signals in the frequency range up to 100 MHz using the optoelectronic switching principle.
Abstract: The response of monolithic arrays of GaAs photoconductors to optical intensity modulation signals and their feasibility of operating as crosspoint arrays in integrated broadband switch matrices are investigated. It is found that individual photoconductors can switch signals at frequencies of up to 1.3 GHz with isolation better than 70 dB and switching time less than 10 ns. In a 2/spl times/2 monolithic array, 65-dB switch isolation and 80-dB crosstalk isolation between channels are achieved in the frequency range 0-130 MHz. The responsivity is essentially uniform within this frequency range and has a value of 0.84 A/W at 820 nm. At higher frequencies electromagnetic coupling between output lines limits the performance with the layout used. This monolithic array thus demonstrates compact broadband matrix switching of signals in the frequency range up to 100 MHz using the optoelectronic switching principle.
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TL;DR: In this article, the voltage responsivity of videodetectors using submicron GaAs Schottky diodes has been investigated in the 0.7-3.7 THz range.
Abstract: The voltage responsivity of videodetectors using submicron GaAs Schottky diodes has been investigated in the 0.7–3.7 THz range. Incident submillimeter power level, DC bias and video-load influences are discussed within the framework of existing theories. Various diodes types differing in semiconductor parameter values as well as junction geometries are compared. The submillimeter frequency response is studied and interpreted in terms of plasma resonance effects in the epilayer.
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TL;DR: In this article, the construction of a fast silicon p doped low temperature bolometer is described, which is a 5 × 5 × 03 mm Si n-type chip whose surface has been implanted with p doses of the order of 1018cm−3.
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TL;DR: In this article, the voltage responsivity of PEM detectors made of graded-gap CdxHg1−xTe structures has been analyzed using a generalized approach, taking into account the x-value and wavelength-dependent material parameters, absorption coefficient and band-to-band recombination time.
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TL;DR: In this paper, the effects of neutron irradiation of AlGaAs/GaAs double hetero-junction photodiodes and special, small active volume, PIN silicon photodors were reported.
Abstract: We report here new results including the effects of neutron irradiation of AlGaAs/GaAs double hetero-junction photodiodes and special, small active volume, PIN silicon photodiodes. Results from high energy electron irradiations are also presented. Finally we report on improvements in processing and growth of these radiation hardened, AlGaAs/GaAs, double heterojunction, photodiodes. Neutron irradiation studies have shown that the double heterojunction, AlGaAs/GaAs photodiodes degrade only slightly after exposure to 3.6 × 1015 n/cm2. The special "rad-hard" silicon PIN photodiodes showed considerably greater degradation in both optical responsivity and leakage current characteristics after exposure to neutron fluences of 1.0 × 1015 n/cm2. Measurements of ionizing-radiation induced photocurrent during exposures to pulsed electron beams and pulsed x-rays show that the AlGaAs/GaAs structures generate only a fraction (0.03 to 0.1) of the current generated by the small active volume, radhard, silicon photodiodes. Optimization of the device growth and fabrication processes have resulted in significantly better electrical characteristics while maintaining good optical properties. The irradiation test results reported here expand our knowledge of the radiation hardness of these devices to include other types of irradiation threats beyond previously published work.
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09 Jan 1984TL;DR: In this article, the combination of a FET switch non-CCD readout architecture with high-quality mesa-photovoltaic indium-antimonide detector material has led to high-performance integrating linear imagers in the 1- to 5-micron region.
Abstract: The combination of a FET switch non-CCD readout architecture with high-quality mesa-photovoltaic indium-antimonide detector material has led to high-performance integrating linear imagers in the 1- to 5-micron region. These devices operate in the temperature regime below 100 K and provide very good dark current and responsivity uniformity (+ or - 2 percent). Test data will show performance at 65 K for a 512-element array and 46 K for a 128-element array. Useful integration times of 3600 seconds at 46 K and greater than 12 seconds at 65 K have been achieved. For both devices, kTC read noise levels of less than 1200 electrons have been measured.
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TL;DR: In this article, a single-mode optical fiber was used for high-data-rate transmission over a single optical fiber using GaAs/GaAlAs channeled substrate planar (CSP) structure laser both as light source and photodetector, which is suitable for semiduplex transmission since the emissive spot and the photosensitive area of the laser coincide.
Abstract: Semiduplex, high-data-rate transmission over a single optical fiber using GaAs/GaAlAs channeled substrate planar (CSP) structure lasers both as light source and photodetector has been demonstrated. The responsivity in the receiving mode at the operating wavelength (830 nm) was 0.15 A/W. This device is suitable for semiduplex transmission, since the emissive spot and the photosensitive area of the laser coincide. The impulse response was measured to be 2.5 ns full width at half maximum (FWHM) at zero bias voltage. A 500-m single-mode fiber was used, and by using microlenses the input coupling loss was reduced to less than 4.5 dB. Measurements at a data rate of 100 Mbit/s return to zero (RZ) shows an optical power margin of 14 dB for a bit error rate (BER) of 10-9. Using lasers instead of LED's as transceivers would improve the transmission capability and the system margin of a semiduplex communication link.
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TL;DR: It is seen that the fabricated devices respond to the frequency of a CO2 laser as a square-law detector and detect the laser signal by rectification due to the nonlinear current-voltage characteristic.
Abstract: The responsivity of antenna-coupled point-contact Schottky diodes to CO2 laser radiation was studied experimentally. the very clear antenna-pattern was obtained for the 10.6 μm radiation and agreed with theory based on the traveling wave antenna. the bias voltage dependence of the detected voltage agreed with the results calculated by using measured dI/dV - V and d2I/dV2 - V characteristics. It is seen from this that the fabricated devices respond to the frequency of a CO2 laser as a square-law detector (resulting from nonlinearity of the I - V characteristic at CO2 laser frequency) and detect the laser signal by rectification due to the nonlinear current-voltage characteristic.
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TL;DR: In this paper, the authors investigated radiation effects on a Ge:Ga photoconductive infrared detector at low photon background level of 4×108 ph cm−2s−1, using Cobalt 60 as a gamma ray source.
Abstract: We have investigated radiation effects on a Ge:Ga photoconductive infrared detector at low photon background level of 4×108 ph cm−2s−1, using Cobalt 60 as a gamma ray source. The irradiation immediately induced spike noises which degrded NEP (short term effect), while it gradually increased responsivity (long term effect). After the removal of the gamma ray source, the spikes disappeared while the responsivity still stayed in a higher level and gradually decreased with a time scale of several hours. The responsivity-change-rate before and after the irradiation is smaller for a higher bias voltage. Finally we have made the first trial to cure the long term effect, using a flashing procedure and have found out its effectiveness.
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TL;DR: In this article, a detailed experimental study of the low frequency (video) response of a quasi-optical Schottky diode detector over the microwave and FIR wavelength range is presented.
Abstract: A detailed experimental study of the low frequency (video) response of a quasioptical Schottky diode detector over the microwave and FIR wavelength range is presented. An optimization of the responsivity versus the bias current is proposed and a generalized curve of the saturation power versus the FIR wavelength is given. This curve defines for any antenna point-contact Schottky diode detector, suitable for FIR detection, the power range for a linear detector response. A simple method is also described to calculate the coupling efficiency of the laser radiation into the antenna reception pattern.
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TL;DR: In this paper, the p-InP/p-InGaAs heterostructure was formed by LPE growth and selective etching from a p-INGaAs/p InGaAs+p-INP/P-INGAAs/InGAAsP/InP multiple-layer heterostrucure with a high barrier-height Schottky contact.
Abstract: Ag/p-InP/p-InGaAs Schottky photodiodes were fabricated with the aim of expanding the spectral response of Ag/p-InP Schottky diodes in the violet and visible region to the infrared region, by adding a p-InGaAs layer to form a heterostructure. The p-InP/p-InGaAs heterostructure was formed by LPE growth and selective etching from a p-InGaAs/p-InP/InGaAsP/InP multiple-layer heterostrucure. A high barrier-height(?0.8 eV) Schottky contact on the Ag/p-InP gave the heterostructure diodes a low reverse leakage current at room temperature. The diodes are shown to have a very wide spectral response, from 0.4 ?m to 1.65 ?m, with a fairly flat responsivity and a response-time of 0.5 ?s when their diameter is 0.4 mm.
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01 Apr 1984
TL;DR: In this article, the Si:Ga system is modeled for detection of infrared (IR) radiation in low backgrounds, and the responsivity and detectivity are calculated as functions of residual B, compensation ratio, and temperature.
Abstract: : The Si:Ga system is modeled for detection of infrared (IR) radiation in low backgrounds. The responsivity and detectivity are calculated as functions of residual B, compensation ratio, and temperature. The results demonstrate a large potential for improvement in device performance if starting material with a low residual B is used to manufacture the detectors. These improvements include higher responsivity, higher operating temperature, increased detectivity, greater uniformity in spatial response, and increased radiation hardness.
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TL;DR: In this article, the authors proposed the fractional-standard deviation as a parameter to describe the non-uniformity of each distribution and applied it to error estimation for luminance measurement of a TV picture tube using a luminance meter composed of a diaphragm, a tube and an illumination meter.
Abstract: Photometric error due to non-uniform responsivity in a photometer aperture is theoretically analyzed for illuminance measurement. Such error is only caused when neither responsivity nor illuminance is distributed uniformly in the aperture of an illumination meter. This error is given by the product of the fractional-standard-deviations in both distributions and the correlation coefficient between them. The fractional-standard-deviation is consequently proposed as a parameter to describe the non-uniformity of each distribution. This theory is validated by applying it to error estimation for luminance measurement of a color TV picture tube using a luminance meter composed of a diaphragm, a tube and an illumination meter. The spacial resolutions required in the measurements of both distributions, which make it possible to precisely estimate the above error, are also discussed. It is revealed that, if the distribution of either responsivity or illuminance is more gradual than the other and sinusoidal, the resolutions should be less than 1/8 the spacial period in which the sinusoidal patterns are repeated.
01 Jan 1984
TL;DR: In this article, an AlGaAs/GaAs double heterojunction, mesa isolated, photodiode grown by molecular beam epitaxy was irradiated with 18 MeV electrons, 1 to 10 MeV x-rays, and neutrons from a pulsed reactor.
Abstract: An AlGaAs/GaAs double heterojunction, mesa isolated, photodiode grown by molecular beam epitaxy was irradiated with 18 MeV electrons, 1 to 10 MeV x-rays, and neutrons from a pulsed reactor. Test results indicate that the AlGaAs/GaAs photodiodes generate approximately 10 to 20 times less photocurrent during exposure to a pulse of ionizing-radiation than radiation hardened silicon PIN photodiodes. Studies of neutron induced permanent damage in the AlGaAs/GaAs photodiode show only small changes in optical responsivity and a factor of 8 increase in leakage currents after exposure to 3.6 x 10/sup 15/ neutrons/cm/sup 2/ and 900 krad gamma. The silicon PIN photodiode was exposed to only 28% of the fluence used on the AlGaAs photodiodes and we observed a 40% decrease in optical responsivity and a factor of 7000 increase in leakage current.
01 Aug 1984
TL;DR: In this article, a bandwidth normalization technique based on analysis of the moments of the spectral responsivity curves was used to analyze the spectral bands of the MSS and TM subsystems of LANDSAT 4 and 5 satellites.
Abstract: The newly built Caste spectropolarimeters gave satisfactory performance during tests in the solar radiometer and helicopter modes. A bandwidth normalization technique based on analysis of the moments of the spectral responsivity curves was used to analyze the spectral bands of the MSS and TM subsystems of LANDSAT 4 and 5 satellites. Results include the effective wavelength, the bandpass, the wavelength limits, and the normalized responsivity for each spectral channel. Temperature coefficients for TM PF channel 6 were also derived. The moments normalization method used yields sensor parameters whose derivation is independent of source characteristics (i.e., incident solar spectral irradiance, atmospheric transmittance, or ground reflectance). The errors expected using these parameters are lower than those expected using other normalization methods.
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TL;DR: In this paper, it is reported that glass-metal seals give rise to photocurrents as a result of light illumination, and the detection performance is of the order of 10 mA·W−1.
Abstract: Ordinary glass–metal seals are reported here to give rise to photocurrents as a result of light illumination. Responsivity observed here is of the order of 10 mA·W−1. Signal-polarity results suggest that the seal acts as a Schottky barrier. Photoionization of impurities, particularly iron oxide, in the glass energy gap is believed to be the detection mechanism. A method is suggested for increasing responsivity. Development of glass optical detectors may be advantageous for many applications involving optics and glass, including integrated optics, particularly in view of the low cost, the completely negligible dark current, and the guiding capabilities of glass fibers. The detection properties of glass–metal seals should be considered when evaluating experimental results, such as the optogalvanic effect, involving discharges as detectors of light.
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26 Dec 1984TL;DR: In this article, it is reported that glass-metal seals are reported to give rise to currents as a result of light illumination, and the sensitivity observed is of the order of 10 mA. Signal-polarity results suggest that the seal acts as a Schottky barrier.
Abstract: Ordinary glass-metal seals are reported here to give rise to currents as a result of light illumination. Responsivity observed here is of the order of 10 mA.W . Signal-polarity results suggest that the seal acts as a Schottky barrier. Photoionization of impurities, particularly iron oxide, in the glass energy gap is believed to be the detection mechanism. A method is suggested for increasing responsivity. Development of glass optical detectors may be advantageous for many applications involving optics and glass, including integrated optics, particularly in view of the low cost, the negligible dark current, and the guiding capabilities of glass fibers. The detection properties of glass-metal seals should be considered when evaluating experimental results, such as the optogalvanic effect, involving discharges as detectors of light.
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TL;DR: The authors showed that vacuum desorption of minority surface impurities increases barrier height and decreases tunneling probability, thus increasing diode nonlinearity and making the diodes more nearly ideal.
Abstract: Desorption of air atoms from point contact diode surfaces via exposure to vacuum can give rise to significant changes in electronic characteristics. In the example considered, exposure of an X-band detector to a modest vacuum gives rise to a responsivity increase of about 80 percent for video and heterodyne detection. Experiments indicate that vacuum desorption of minority surface impurities increases the barrier height and decreases tunneling probability, thus increasing diode nonlinearity and making the diodes more nearly "ideal." The resulting relative increase of the thermionic emission current should decrease the effective shot-noise temperature, thus increasing the signal-to-noise ratio (SNR) even further.