Showing papers on "Responsivity published in 1993"
TL;DR: In this article, the Schottky barrier photodetectors on p-type GaN films were fabricated over basal plane sapphire substrates using low pressure metalorganic chemical vapor deposition and magnesium as the p type dopant.
Abstract: In this letter we report the fabrication and characterization of Schottky barrier photodetectors on p‐type GaN films. These films were grown over basal plane sapphire substrates using low pressure metalorganic chemical vapor deposition and magnesium as the p‐type dopant. The current‐voltage and capacitance‐voltage characteristics were measured for Ti/Au Schottky barriers for a film with a p doping of 7×1017 cm−3. We measured a 1.5 V forward turn on and a 3 V reverse breakdown. The zero bias responsivity of a detector with 1 mm2 area was measured to be 0.13 A/W. For these photovoltaic detectors, the photoresponse was nearly constant from 200 to 365 nm and fell sharply by several orders of magnitude for wavelengths above 365 nm.
181 citations
TL;DR: In this article, the Andreev reflection of electrons and weak electron-phonon coupling at low temperatures is exploited to produce a large temperature rise for a small input power (≊10 mK/fW).
Abstract: We present measurements on a novel power detector which can be used as an ultrasensitive detector of millimeter and submillimeter radiation. The absorbing element consists of a thin film resistor strip which is connected to superconducting electrodes. This device exploits the Andreev reflection of electrons and the weak electron‐phonon coupling at low temperatures to produce a large temperature rise for a small input power (≊10 mK/fW). The temperature rise of the electrons is detected by a tunnel junction where part of the metal strip forms the normal electrode. We have measured a voltage responsivity of approximately 109 V/W and an amplifier‐limited electrical noise equivalent power ≊3×10−18 W Hz−1/2 at an operating temperature of 100 mK. If infrared radiation were efficiently coupled to the absorbing element with an antenna or a waveguide, then the sensitivity of this detector would be at least a factor of 10 better than the best available direct detector operating at the same temperature.
179 citations
TL;DR: SiC photodiodes were fabricated using 6 H single-crystal wafers as discussed by the authors, which have excellent UV responsivity characteristics and very low dark current even at elevated temperatures.
Abstract: SiC photodiodes were fabricated using 6 H single-crystal wafers. These devices have excellent UV responsivity characteristics and very low dark current even at elevated temperatures. The reproducibility is excellent and the characteristics agree with theoretical calculations for different device designs. The advantages of these diodes are that they will operate at high temperatures and are responsive between 200 and 400 nm and not responsive to longer wavelengths because of the wide 3-eV bandgap. The responsivity at 270 nm is between 70% and 85%. Dark-current levels have been measured as a function of temperature that are orders of magnitude below those previously reported. Thus, these diodes can be expected to have excellent performance characteristics for detection of low light level UV even at elevated temperatures. >
168 citations
TL;DR: In this article, the Hamamatsu S1337 photodiode was found to be the best suited for use as a high accuracy transfer standard for both the visible and UV spectral regions.
Abstract: Different types of photodiode have been characterized with respect to uniformity, linearity, stability of responsivity and temperature coefficient at several wavelengths between 257 nm and 799 nm based on cryogenic radiometry and intensity stabilized lasers. The Hamamatsu S1337 photodiode was found to be the best suited for use as a high accuracy transfer standard for both the visible and UV spectral regions. For low-level radiant power measurement, this kind of photodiode can be calibrated via a cryogenic radiometer with a total uncertainty as low as ±0,02% in the visible and ±0,25% in the UV.
76 citations
TL;DR: In this paper, the authors derived analytical results for the intersubband absorption quantum efficiency, which take into account contributions from both bound-to-bound state and bound−to-continuum state transitions.
Abstract: Analytical results are derived for the intersubband absorption quantum efficiency, which take into account contributions from both bound‐to‐bound state and bound‐to‐continuum state transitions. Including the final state lifetime broadening, the absorption spectrum gradually decreases in peak strength and becomes broader from the pure bound‐to‐bound case to the pure bound‐to‐continuum situation. The physical reason for the divergence in absorption strength when the upper state is in resonance with the top of the barrier and in the absence of broadening is discussed. The detector current responsivity as a function of well width (and hence upper state position) is estimated. Calculated examples are given, covering the crossover region from the bound‐to‐bound case to the bound‐to‐continuum case. Our results compare well with experiments.
70 citations
TL;DR: In this article, a two-color infrared detector using GaAs/AlGaAs and strained InGaAs/alGaAs multiquantum wells is demonstrated, and the response peak of the two-colour detector is at 8 μm.
Abstract: A two‐color infrared detector using GaAs/AlGaAs and strained InGaAs/AlGaAs multiquantum wells is demonstrated. The response peak of the GaAs/AlGaAs quantum well is at 8 μm, and that of the InGaAs/AlGaAs quantum well is at 5.3 μm. The responsivity of the detector is 1 A/W at 8 μm and 0.27 A/W at 5.3 μm; these are the best values reported for a two‐color quantum well infrared detectors (QWIPs) with peak sensitivities in the spectral regions of 3–5.3 μm and 7.5–14 μm. Single‐colored 5.3 and 8 μm QWIPs were also fabricated to study the bias dependent behavior. This behavior can be explained using the concept of current continuity. Because of a higher electrical resistance, a high electric field domain is always formed first in the shorter wavelength quantum well stack.
65 citations
TL;DR: In this paper, a metal-semiconductor-metal (MSM) photoconductor and a pn photodiode have been fabricated from rapid-thermal-oxidized (RTO) porous Si.
Abstract: A metal‐semiconductor‐metal (MSM) photoconductor and a p‐n photodiode have been fabricated from rapid‐thermal‐oxidized (RTO) porous Si. The MSM photoconductor achieved 2.8×higher responsivity at 350 nm than a UV‐enhanced Si photodiode, and the RTO photodiode exhibited an external quantum efficiency of 75% at 740 nm.
51 citations
TL;DR: In this article, the high frequency saturation characteristics of an InGaAs/InP waveguide pin photodetector were measured at a wavelength of 1.3 μm.
Abstract: The high frequency saturation characteristics of an InGaAs/InP waveguide pin photodetector are measured. At a wavelength of 1.3 μm, the detector has a responsivity of 0.5 A/W and a flat frequency response from 800 MHz to 20 GHz. With a bias of −4 V, the normalised frequency response of the detector remains unchanged when optical powers up to l0 mW are incident on the detector.
48 citations
TL;DR: In this paper, the authors performed an extensive series of measurements on symmetrical barrier bound-to-continuum and asymmetric barrier bound -to-bound quantum well infrared photodetectors consisting of only a single well.
Abstract: We have performed an extensive series of measurements on symmetrical barrier bound‐to‐continuum and asymmetrical barrier bound‐to‐bound quantum well infrared photodetectors consisting of only a single well. We find that the behavior of the optical (e.g., responsivity) and transport properties (e.g., gain) as a function of bias is strikingly different from that of the usual multi‐quantum well detectors. The simplicity of the structure has allowed an accurate theoretical calculation of the potential drops across each barrier, the photoinduced carrier depletion in the quantum well and therefore a detailed understanding of the device physics.
38 citations
TL;DR: In this article, an undoped single-quantum-well infrared photodetector with electron tunneling through the thin emitter barrier is presented, which exhibits a unity optical gain and a dramatic drop in the well carrier density at high bias when the bound state of the well drops below the emitter conduction-band edge.
Abstract: An extensive series of measurements and theoretical analysis are presented on an undoped single‐quantum‐well infrared photodetector. The well is filled by electron tunneling through the thin emitter barrier resulting in several novel characteristics compared with the usual directly well‐doped detectors. These include a unity optical gain and a dramatic drop in the well carrier density (and responsivity) at high bias when the bound state in the well drops below the emitter conduction‐band edge.
38 citations
TL;DR: In this article, the optical transmittance of indium-tin oxide (ITO) at a wavelength of 1.3 mu m has been improved by adding forming gas (H/sub 2/N/Sub 2/) to the Ar sputtering gas.
Abstract: The optical transmittance of indium-tin oxide (ITO) at a wavelength of 1.3 mu m has been improved by adding forming gas (H/sub 2//N/sub 2/) to the Ar sputtering gas. It is shown that the presence of H/sub 2/ in the plasma decreases the carrier concentration in ITO and increases the optical transmittance of a 320 nm-thick ITO film from 69.7% to 99.5%. The application of the high transmittance ITO to the fabrication of metal-semiconductor-metal (MSM) photodiodes on InAlAs/InGaAs heterostructures has resulted in an improvement of responsivity from 0.6 A/W to 0.76 A/W. This is double the responsivity of 0.39 A/W obtained for Ti/Au detectors. A 3-dB bandwidth of 6 GHz was obtained for the high transparency ITO device with 3 mu m fingers and gaps and with an area of 50 mu m*50 mu m. >
TL;DR: In this paper, a detailed study of a wide variety of quantum well infrared photodetectors, which were chosen to have large differences in their optical and transport properties, is presented.
Abstract: The author presents a detailed study of a wide variety of quantum well infrared photodetectors, which were chosen to have large differences in their optical and transport properties. Intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasicontinuum and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot-carrier mean free path, net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity.
TL;DR: In this article, GaAs was grown on Si substrates by molecular-beam epitaxy at low substrate temperatures and femtosecond time-resolved reflectivity investigations revealed a significant reduction of carrier lifetime in GaAs epilayers from 14 ps to <0.5 ps as the growth temperature was reduced from 400 to 150 °C.
Abstract: GaAs was grown on Si substrates by molecular‐beam epitaxy at low substrate temperatures. Femtosecond time‐resolved reflectivity investigations revealed a significant reduction of carrier lifetime in GaAs epilayers from 14 ps to <0.5 ps as the growth temperature was reduced from 400 to 150 °C. Photoconductors were fabricated on the epilayers, and electro‐optic sampling was used to confirm the electrical response times of <1 ps. The responsivity is comparable to that for low‐substrate‐temperature GaAs grown on GaAs substrates, with a photogenerated carrier mobility of ∼100–300 cm2/V s. The low growth temperatures allow ultrafast GaAs‐based photodetector incorporation into Si‐based integrated circuits for novel optoelectronic applications.
21 Jun 1993
TL;DR: In this paper, a multicolor QWIP (quantum-well infrared photodetector) was proposed by stacking the usual one-color qWIPs separated by thin (approximately 100 nm in the present test structure) conducting layers.
Abstract: Summary form only given. The authors present a novel concept of a multicolor QWIP (quantum-well infrared photodetector) by stacking the usual one-color QWIPs separated by thin ( approximately=100 nm in the present test structure) conducting layers. They rely on the highly nonlinear and exponential nature of the device dark current-voltage characteristics. This implies that an applied voltage across the entire multistack would be distributed among the one-color QWIPs according to their values of DC resistances. Thus, when the applied voltage is increased from zero, most of the voltage will be dropped across the one-color QWIP with the highest resistance. As the voltage is further increased, an increasing fraction of the voltage will be dropped across the next highest resistance one-color QWIP, and so on. Since the detector responsivity of a one-color QWIP gradually turns on with applied voltage, one therefore can achieve a multicolor QWIP with spectral response peaks that turn on sequentially with an applied voltage. To demonstrate this concept, a three-color version of the multicolor QWIP has been fabricated. >
Journal Article•
05 Jan 1993
TL;DR: In this article, it was shown that very high current responsivities and high gain are obtained when approaching detector voltages close to -8.5 V, which is explained by carrier impact excitation of electrons from the QW ground state to the excited extended state.
Abstract: In0.53Ga0.47As/InP infrared detectors with peak absorption at a wavelength of 8.5 micrometers have been fabricated and tested. It is shown that very high current responsivities and high gain are obtained. It is found that gain increases drastically when approaching detector voltages close to -8.5 V, which is explained by carrier impact excitation of electrons from the QW ground state to the excited extended state. The detectivity D* is about 1.2(DOT)1010 cm Hz1/2 W-1 at 80 K for a 45 degree(s) polished edge detector assuming unpolarized radiation. Grating coupling is studied by etching crossed gratings into the upper part of the mesas. The increase in responsivity as compared to a polished edge detector is by a factor of 2.5 to 3, irrespective to mesa sizes 500 X 500 or 150 X 150 micrometers 2. This gives a corresponding detectivity of (3 - 3.5)(DOT)1010 cm Hz1/2 W-1 at 80 K for unpolarized radiation.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this paper, the properties of a new large area InGaAs photodiode with near unity internal quantum efficiency are described and compared with measurements on germanium photodiodes.
Abstract: The paper describes the properties of a new large area InGaAs photodiode with near unity internal quantum efficiency. Measurements of linearity, spatial uniformity and dark current of the photodiodes are presented and compared with measurements on germanium photodiodes. The paper also describes the performance of a detector constructed from an arrangement of three of these photodiodes and shows how it has a calculable responsivity from 980 nm to 1 640 nm. It also describes how such a detector can be used as a sensor for a fibre-optic power meter with an uncertainty of around 0,1%.
TL;DR: In this paper, the authors compared the performance of thin-film epitaxial lift-off (ELO) photodetectors with and without back passivation, and showed that passivated ELO detectors perform comparably to the on-wafer devices, while the unpassivated devices exhibit performance degradation.
Abstract: High-performance thin-film epitaxial lift-off (ELO) photodetectors have potential for integration with independently optimized integrated circuits and waveguides. In this paper, the dark current, responsivity, and frequency response of GaAs/AlGaAs metal-semiconductor-metal (MSM) photodetectors that remain on the growth substrate are compared to ELO detectors with and without back passivation. The passivated ELO detectors perform comparably to the on-wafer devices, while the unpassivated devices exhibit performance degradation. In addition to demonstrating the importance of back passivation, this paper presents the lowest ELO MSM dark current (5 nA at 5 V) for a 200- mu m-diameter device published to date. >
TL;DR: In this paper, the electrical and photo-electrical properties of the longwavelength n + πp + Hg 1− x Cd x Te structures have been analyzed numerically.
TL;DR: In this article, the photovoltaic effect in a quantum ballistic channel (QBC) with a non-uniform narrowed end was investigated, and the authors used a mode-matching technique to obtain the photocurrent.
Abstract: Photon-induced intersubband scattering in a quantum ballistic channel (QBC) is investigated. The authors calculations show that light absorption in QBC with a non-uniform narrowed end can lead to a photovoltaic effect. Using a mode-matching technique the photocurrent is obtained. The evaluated responsivity, detectivity and band width of the proposed photovoltaic detector are conducive to practical application.
TL;DR: In this paper, a pigtailed transceiver module which exhibits a record responsivity of 0.5 A/W is described, where a single laser chip of Fabry-Perot type V-on-U-groove (VUG) laser is packed in a butterfly type package.
Abstract: A pigtailed transceiver module which exhibits a record responsivity of 0.5 A/W is described. A single laser chip of Fabry-Perot type V-on-U-groove (VUG) laser is packed in a butterfly type package. By improving the fibre-chip coupling, a responsivity as high as 0.5 A/W is demonstrated together with a bandwidth of 1.5 GHz. The power penalty, compared with that of a p-i-n photodiode within the same experimental configuration, is only 1.2 dB at 800 Mbit/s. >
TL;DR: In this paper, the authors carried out high resolution spatial measurements of the surface reflectance and responsivity of single and trap-configured silicon photodiodes at laser wavelengths between 325 nm and 780 nm.
Abstract: We have carried out high resolution spatial measurements of the surface reflectance and responsivity of single and trap-configured silicon photodiodes at laser wavelengths between 325 nm and 780 nm. The results indicate that the spatial nonuniformity of quantum efficiency for a given photodiode varies with laser wavelength and internal structure. For radiometric quality diodes this nonuniformity of response leads to uncertainties in detector measurements which can be reduced to 0,03% or better.
TL;DR: In this paper, the photoresponses of Pb doped 2223 phase BiSrCaCuO films to low power 5 mm cw radiation were measured at temperatures near Tc.
Abstract: The photoresponses of Pb doped 2223 phase BiSrCaCuO films to low power 5 mm cw radiation were measured at temperatures near Tc. To identify the involved detection mechanisms, dependence of responsivity on temperature, supplied current, radiation power, and film granularity were investigated. At temperatures in the vicinity of the transition to the normal state, good agreement was obtained with the responses derived from a bolometric model. At temperatures below the transition, a nonbolometric response mode was found to occur when the film was biased into a partially resistive regime. Transient measurements were carried out showing a response time for this mode of at least 5 orders of magnitude smaller than that of the bolometric response. Further characteristics inherent to the nonbolometric mode include square law detection, nonlinear current dependence, and short wavelength cutoff. In addition, a correlation between responsivity and film granularity was established. For strongly granular films with an a...
TL;DR: In this paper, a 1.3 mu m waveguide-coupled strained-layer In/sub x/Ga/sub 1-x/As/GaAs detector with an optimized active layer thickness was reported.
Abstract: The design and fabrication of a 1.3- mu m waveguide-coupled strained-layer In/sub x/Ga/sub 1-x/As/GaAs MSM detector with an optimized active layer thickness is reported. For 100- mu m-long devices, a responsivity of 0.58 mA/mW is observed. Using the detector as an optoelectronic switch, on/off ratios better than 40 dB were achieved at L and X band. >
TL;DR: In this article, the authors measured the electrical and radiometric properties of a cryogenic bolometer/amplifier which is intended for use as a transfer standard in an infrared spectral comparator facility under development at the NIST.
Abstract: We have measured the electrical and radiometric properties of a cryogenic bolometer/amplifier which is intended for use as a transfer standard in an infrared spectral comparator facility under development at the NIST. We have found its sensitivity to be similar 20 pW, instability <1%, responsivity similar 1,7 × 106 V/W, spatial nonuniformity <1% and nonlinearity <1% over five decades. These results show that this device can be used for its intended purpose as an IR detector transfer standard.
TL;DR: In this paper, the design of a high temperature bolometer with large area that uses the resistive transition of a Bi2Sr2CaCu2O8+x superconducting thin film as a sensitive thermometer is discussed.
Abstract: The design of a high‐temperature bolometer with large area that uses the resistive transition of a Bi2Sr2CaCu2O8+x superconducting thin film as a sensitive thermometer is discussed. Load curve analysis and discussion of nonthermal behavior are presented. Measurements of the electrical noise voltage spectrum and the analysis of the optical response performed with a chopped He‐Ne laser at λ=633 nm gave a zero‐frequency responsivity between 1.3 and 2.4 V/W and a noise equivalent power of 1×10−8 W/Hz1/2 in the frequency range 2–10 Hz, with an effective time response of 1.5 s. Measurements of the excess noise voltage for different values of the bias current and temperature are used in order to predict the performances of a suitable bolometric composite architecture.
TL;DR: In this paper, a bolometric model was proposed to calculate the temperature rise and responsivity of the bolometer in granular YBa/sub 2/Cu/sub 3/O/sub 7- delta / films using microbridge structure.
Abstract: The optical response of granular YBa/sub 2/Cu/sub 3/O/sub 7- delta / films using microbridge structure was investigated. Considering the self-heating effect of the detector from the bias current, a bolometric model was proposed to calculate the temperature rise and responsivity of the bolometer. The responsivity of a nonequilibrium detector on the basis of grain boundary Josephson junctions in granular films has also been demonstrated. Optical detectors with responsivities of more than 10/sup 3/ v/w at liquid nitrogen temperature have been fabricated. Experimental evidence for the coexistence of bolometric and nonbolometric effect is given. Calculations based on the proposed model are in agreement with the experimental results. >
TL;DR: In this paper, the authors fabricated YBCO thin films by RF magnetron sputter deposition onto ZrO/sub 2/, SrTiO/ sub 3, LaAlO/Sub 3, and MgO substrates and patterned these films into microbolometers.
Abstract: The authors fabricated YBCO thin films by RF magnetron sputter deposition onto ZrO/sub 2/, SrTiO/sub 3/, LaAlO/sub 3/, and MgO substrates and patterned these films into microbolometers. The influence of substrate type and device biasing current on the response of the microbolometers was measured. The responsivity and the speed of the devices were found to depend on the thermal conductivity of the substrates used. The fastest YBCO device was found on MgO, whereas the largest bolometric response was found on ZrO/sub 2/. It was found that the responsivity of a microbolometer increased with biasing current, but there was an optimal biasing current beyond which device performance deteriorated due to self heating. The results indicate that the most sensitive microbolometer requires a sharp YBCO resistivity transition, a low thermal conductivity substrate, and an optimal biasing current. >
Patent•
13 Sep 1993TL;DR: In this article, a process for fabricating a front surface resonant mesh array detector produces a detector of reduced size, which results in enhanced responsivity and minimizes thermal stress between the detector and typical array substrates.
Abstract: A process for fabricating a front surface resonant mesh array detector produces a detector of reduced size. The reduced size results in enhanced responsivity, and minimizes thermal stress between the detector and typical array substrates, enabling fabrication of arrays using front surface resonant mesh array detectors.
TL;DR: In this paper, the fabrication and characteristics of high-performance large-area InP:Fe/InGaAs:Fe:Fe metal-semiconductor-metal (MSM) photodetectors are reported.
Abstract: The fabrication and characteristics of high-performance large-area InP:Fe/InGaAs:Fe/InP:Fe metal-semiconductor-metal (MSM) photodetectors are reported. With a 350- mu m*350- mu m active area, the detectors offer 900-MHz electrical bandwidth and 1.7-pF capacitance at 10-V bias. The respective dark current density is 20 pA/ mu m/sup 2/, an the CW responsivity is 0.4 A/W at 1.3- mu m wavelength. The detectors are therefore ideally suited for applications in the long-wavelength range that require a large detection area and, at the same time, a high bandwidth and low capacitance. >