Photoconductive detectors responsivity

Poly Chlorinated Biphenyls. The photoconductivity detector provides good responses for polychlorinated biphenyls separated by GPC. The normal matrix components are detected by RI and UV detectors while the polychlorinated species show high responses in the electrochemical detector (Figure 8). ... 

The first apparent report in the open literature of CD PbSe for photoconductive detectors was in 1949 [53], The PbSe was deposited from a solution of PbAci and selenourea onto a predeposited (from PbAci and thiourea) layer of PbS. The PbS layer acted as a seed layer, presumably to obtain faster deposition (it was noted that the PbSe deposition was much slower than that of PbS). The photoconductivity of this film exhibited a broad maximum between 3 and 4 p,m, giving a reasonable response out to beyond 4.5 p,m (PbS drops off at 3 iJim). 

FIGURE 2 Responsivity as a function of wavelength for AlGaN photoconductive detectors with various aluminium compositions [7],... 

F. R. Arams, E. W. Sard, B. J. Peyton and F. P. Pace, Infrared Heterodyne Detection with Gigahertz IF Response H. S. Sommers, Jr., Macrowave-Based Photoconductive Detector... 

Thermal and photoconductive detectors are used to measure radiation intensities, but all have relatively slow responses and are subject to drift. The lead sulfide or telluride photoconductive cell has a response time of about 0.5 ms, but sensitivity decreases sharply above 2900 cm" for the sulfide and above 1700 cm- for the telluride. Thermal detectors are employed at longer wavelengths. The simplest of these is the thermocouple, which has a relatively slow response (about 60 ms), and several are usually linked to form a thermopile. Bolometers... 

The type of detector used in an FT-IR spectrometer is highly dependent upon the bandwidth (i.e. the spectral frequencies), the modulation rate of the interferometer, and the intensity of the radiant flux. Several types of detectors are used in the infrared regions photoconductive, photovoltaic, bolometers, pyroelectric and Golay cells. A detailed discussion of detectors may be found elsewhere.12 In general, the photovoltaic and photoconductive detectors can be used in the near- and mid-infrared regions as rapid response, high sensitivity detectors. Usually the bandwidths are limited and will not cover the total ran passed by the beamsplitter. Examples of such detectors are given in Table I. As can be seen from the... 

The speed of response of an intrinsic photoconductive detector is essentially the same as the longest photoexcited carrier lifetime. One can shorten the response time of a detector of this kind by biasing it as far as possible into the sweepout mode, since the effective minority carrier lifetime r/(z) is reduced in proportion to the bias field. 

Thus the zinc blende structure semiconductors can be useful for intrinsic photoconductive detectors. Compounds such as InSb have been used as intrinsic photoconductors [4.20], as well as for photovoltaic detectors, but greater versatility of wavelength response is possible with the Hg j tCd Te alloy system. The Hgi j.Cd,Te alloys have received considerable development effort in recent years and are the most prominent intrinsic photoconductor materials they will be analyzed in this subsection. The development of Hg, Cd Te has concentrated almost entirely on n-type material since it provides high photoconductive gain however, p-type Hg, Cd,(Te crystals may be useful for intrinsic photoconductive detectors also [4.21]. 

Solanki CS, Bilyalov RR, Poortmans J, Nijs J, Mertens R (2004) Porous silicon layer transfer processes for solar cells. Solar Energy Mater Solar Cells 83 101-113 Suhail AM, Naji AN, Muhammed GS, Thjeel HA, Al-zaidi QG (2012) Fast response ZnO/porous silicon UV photoconductive detector. Int J Thin Film Sci Teehnol 1(1) 35—42 Vasin AV, Ishikawa Y, Shibata N, Salonen J, Lehto VP (2007) Carbonization of porous silicon for 3C-SiC growth. Mater Sci Forum 556-557 167-170 on Wiesner M, Angelopoulos EA, Rossbach R, Jetler M, Michler P (2009) GaAs-growth porous silicon. EW-MOVPE Xlll, Ulm, C.06... 

A Ge Ga photoconductive detector at lOOym and a GaAs epitaxial photoconductive detector at 285ym has been optimized for sensitivity comparison with a conventional bolometer system of Yerkes Observatory. The response of the photoconductive detectors were studied in the laboratory under two background conditions baffles and Fabry Optics. A direct comparison of the photoconductive detectors to the bolometer will be made on the 91.5 cm telescope aboard the NASA C-141 Airborne Infrared Observatory. 

An infrared detector converts the incident infrared radiation to electric signals. If the electric signal from a detection system (a detector and associated electronics) is not proportional to the intensity of the incident infrared radiation, in other words, if the detector response is nonlinear, this nonlinearity causes distortion in the measured interferogram. As a result, the infrared spectrum calculated from the distorted interferogram has inaccurate intensities, which may lead to deviations from Lambert-Beer s law. Such nonlinearity does not occur with a detection system with a pyroelectric TGS (triglycine sulfate) detector, but it may arise in the detection system with a photoconductive MCT detector. 

The time response of a photoconductive detector is limited by the carrier lifetimes. PbS detectors for instance have time constants between 0.1 - 1 ms while InSb detectors reach a few us. For measurements of fast transient signals photodiodes are more suitable (see Sect.4.5.8). 

Beck Binomax stereo-microscope mounted over the DSC sample holder. The light detector was a Vickers CdS photoconductive cell which had a large light-sensitive area and a maximum response at 545 nm. The signal from the detector was amplified by a operational amplifier. Both DSC and light detector cell signals were recorded on a strip-chart recorder. 

This graph summarizes the wavelength response of some semiconductors used as detectors for infrared radiation. The quantity D (X) is the signal to noise ratio for an incident radiant power density of 1 W/cm and a bandwidth of 1 Hz (60° field of view). The Ge, InAs, and InSb detectors are photovoltaics, while the HgCdTe series are photoconductive devices. The cutoff wavelength of the latter can be varied by adjusting the relative amounts of Hg, Cd,... 

A photoconductive cell is an important selective detector. Such cells show an increase in conductivity when illuminated with infrared light, and they have high sensitivity with fast response. These cells are used extensively in the spectral region... 

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