Showing papers on "Responsivity published in 1973"

Thin metal film room-temperature IR bolometers with nanosecond response time

Abstract: The experimental and theoretical investigation of thin-film metal (bismuth, antimony, chromium, nickel) bolometers on beryllium oxide substrates is described. Responsivity, sensitivity (NEP), and time response data for each type of metal bolometer are compared with the results obtained from a thermal analysis of the bolometer. Thin-film bismuth devices can have a responsivity of 2.2 \times 10^{-2} V/W and an NEP of 5.0 \times 10^{-8} W/Hz1/2with nanosecond response time. We report measurement of 2- ns response times for bismuth-film bolometers and calculated subnanosecond response times with thinner film devices. These results show that room-temperature thin-film, metal-bolometer IR detectors should be capable of detecting nanosecond and subnanosecond rise-time IR pulses with peak power levels of the order of a few milliwatts.

Characteristics of infrared photodetectors produced by radiation doping

Abstract: High‐energy electrons (≈7 MeV) were used to radiation dope extrinsic silicon. Both n‐ and p‐type silicon photodetectors were fabricated using this doping technique. The 500°K blackbody responsivity, spectral response, and peak detectivity were determined for these devices. The peak detectivity values measured were 4.8×1011 cm Hz1/2 W−1 at 2.15 μ for 0.1‐Ω cm n‐type devices and 3.7×1011 cm Hz1/2 W−1 at 40 μ for 10‐Ω cm p‐type detectors. A comparison of the thermally generated background majority carrier concentration for radiation‐doped and conventional impurity‐doped detectors is made.

Lateral photodetector of improved sensitivity

Abstract: A lateral photodetector of improved sensitivity and method of making the e. The photodetector consists of semiconductive wafer, having a transparent layer of metal deposited on its front face to form a Schottky barrier. A negative bias is applied to the Schottky barrier to form a depletion region in the wafer. A low resistivity layer is formed on back of the wafer to which four signal electrodes are attached. Before forming the cell, the semiconductor wafer was exposed to nuclear radiation to increase the responsivity of the cell.

The design, fabrication, and evaluation of a silicon junction field-effect photodetector

Abstract: A new device for photodetection is introduced in this study that is capable of responsivities comparable to devices operating in the charge-storage mode. Since the physical process involved corresponds to a photodiode in series with a high value of resistance, the device operates in real time and hence avoids the problems of switching encountered in the charge-storage mode at low light levels. The device utilizes this physical process in a new technique that significantly reduces the required surface area. Although the junction field-effect transistor (FET) serves as the prototype for the device, considerations for improving the magnitude of the output response and its linearity along with the responsivity-bandwidth product lead to a device having a very low transconductance _{m} and a large cutoff voltage V GC . Field-effect photodetectors fabricated in accordance with the principles developed for optimum photodetection are evaluated. Epitaxial silicon of conventional doping was used in the fabrication. The devices are found to exhibit the photodetecting characteristics expected from theoretical considerations. A simple two-lump approximation of the distributed gate-channel interface is found to adequately describe the frequency response of the devices. In contrast to the area-independent responsivity of the charge-storage mode, it is shown that the responsivity of the field-effect photodetector is proportional to the square of the device surface area. Depending upon the illumination level and the deviation from linearity that is tolerable, this area dependence presents one of the fundamental drawbacks of the field-effect photodetector for applition in dense arrays.

A simple, electrical calibration technique for bolometer detection systems

Abstract: A simple, purely electrical technique for determining the responsivity of a bolometer detection system is presented. This technique is easy to use and allows the system to be calibrated under actual operating conditions.

A new grating-type gold-n-type silicon Schottky-barrier photodiode

Abstract: The new grating-type Au-n-type Si Schottky-barrier photodiode has been fabricated and analyzed. The device is constructed with a new structure of contact mask. The mask forms a grating of gold film over the contacting silicon substrate. The grating spacing is so chosen that even at zero bias the interfacial layer between the silicon substrate and the gold gratings is completely depleted. The device is fabricated on an n-type silicon wafer of ∼1300-Ω.cm resistivity, and the grating spacing is 12.5 µm. An analysis is performed to determine the I-V characteristics, the spectral dependence of the quantum yield, the responsivity, and the noise characteristics of the photodiode. It is found that without optimization the device has a bandwidth of ∼1 GHz and responsivity of 0.63 A/W at λ =0.9 µm.

Method and means for equalizing the response of signal channels in a multiple channel improved system

Abstract: Automatic responsivity control in a multiple channel infrared system is realized by means of reference signals derived from a modulated light source. The light source illuminates both the infrared element array and a separate reference signal detector. The infrared video signal and the reference signals transmitted in each infrared system channel are passed through a variable gain amplifier. The gain of the variable gain amplifier (and hence the magnitude of the reference signal) is controlled by a circuit including a synchronous filter, a synchronous detector, a DC reference voltage source, and a voltage controlled resistor. The separate reference signal detector provides drive signals to control the synchronous filter and also provides a 180* phase shifted reference signal that is used to cancel the reference signal in the output of the variable gain amplifier.

Investigation of responsivity and noise in a direct-coupled photodetector-preamplifier for facsimile cameras

Abstract: The direct-coupled (DC) mode of detector operation is evaluated for use in a facsimile camera. Photodiode-preamplifier sensitivity is described in terms of photodiode responsivity and possible noise sources resulting from the photodiode and preamplifier. Responsivity and noise limitations are experimentally verified and used to predict photodiode-preamplifier sensitivity under a wide range of operating conditions. Results demonstrate that the DC mode offers advantages in sensitivity and reduced mechanical complexity for facsimile cameras over the more common technique of chopping the radiation and ac amplifying the resultant signal.

Improved responsivity and sensitivity characteristics of the thin-film bismuth bolometer

Abstract: A new design for the nanosecond response time room-temperature thin-film bismuth bolometer has resulted in much improved responsivity and sensitivity characteristics. A responsivity of 2.20 \times 10^{-2} V/W and a sensitivity (NEP) of 5.0 \times 10^{-8} W/Hz1/2is reported. This is an improvement by a factor of 45 for the responsivity and a factor of 70 for the sensitivity over that previously reported for the bismuth-silver bolometer.

Growth of potassium tantalate dielectric crystals and their application as photovoltaic UV detectors

Abstract: Large single crystals ( 5 \times 5 \times 4 cm) of KTaO 3 have been grown by the Czochralski method The growth parameters and electrical properties have been investigated Crystals were grown either highly insulating ( >10^{14}\Omega ) or semiconducting n-type depending upon growth conditions Photovoltaic cells were made by contacting the KTaO 3 with either evaporated thin metal films or silver paint The ultraviolet (UV) responsivity and detectivity of an ac photovoltaic cell using KTaO 3 has been measured Under no-bias conditions the responsibity was 70 \times 10^{6} V/W and the detectivity, D λ *, was \sim 10^{12} cm Hz1/2/W at 3000A measured a t 20 Hz Other properties are also discussed

Far-Infrared Grating Spectrometer Using a Tunable InSb Detector

Abstract: An InSb detector in a magnetic field has narrow spectral band responsivity and tunability due to the cyclotron resonance absorption. A far-infrared grating spectrometer using the tunable InSb detector has been designed and constructed for measurements in the frequency range from 33 to 333 cm-1. This spectrometer is so simple that it consists of only two scatter plates and a cooled filter. Performance of the spectrometer has been examined. The spectral purity is estimated to be larger than 99% under a certain condition, and the spectral reproducibility is sufficiently high. The spectral resolutions of 0.3 cm-1 at 38 cm-1 and 55 cm-1 are obtained. A fast spectrometer with the wavelength scanning speed exceeding ten times the one of the conventional instruments has been made.

Optimization of responsivity in millimeter and submillimeter glow discharge detectors

Abstract: A simplified theory that allows determining optimum gas composition and pressure needed to maximize the responsivity of millimeter and submillimeter glow discharge detectors at a given spectral frequency is presented together with experimental verification.