Solid-state detector charge-coupled device

P. G. LeComber and W. E. Spear, The Development of the a-Si H Field-Effect Transistor and Its Possible Applications D. G. Ast, a-Si H FET-Addressed LCD Panel S. Kaneko, Solid-State Image Sensor M. Matsumura, Charge-Coupled Devices M. A. Bosch, Optical Recording A. D Amico and G. Fortmato, Ambient Sensors H. Kukimoto, Amorphous Light-Emitting Devices R. J. Phelan, Jr., Fast Detectors and Modulators J. I. Pankove, Hybrid Structures... 

A photomultiplier tube is a sensitive detector of visible and ultraviolet radiation photons cause electrons to be ejected from a metallic cathode. The signal is amplified at each successive dynode on which the photoelectrons impinge. Photodiode arrays and charge coupled devices are solid-state detectors in which photons create electrons and holes in semiconductor materials. Coupled to a polychromator, these devices can record all wavelengths of a spectrum simultaneously, with resolution limited by the number and spacing of detector elements. Common infrared detectors include thermocouples, ferroelectric materials, and photoconductive and photovoltaic devices. 

The latest designs in area detectors employ charge-coupled devices (CCDs) as detectors. In effect, CCDs are photon counters, solid-state devices that accumulate charge in direct proportion to the amount of light that strikes them. They have found use in astronomy as light collectors of great sensitivity. For... 

Although most of the radiation sources for AAS are LSs, the great advances in detector technology, especially the development of solid-state array detectors and charge-coupled devices (CCDs), have led to the successful application of continuous sources (CSs) for AAS. A modern CS is based on a conventional xenon short-arc lamp that has been optimized to run in the so-called hot-spot mode.9 This discharge mode requires the appearance of a small plasma spot close to the cathode... 

The classical silicon photodiode linear array manufactured by Reticon was the first detector marketed successfully. Similar solid state linear array detectors based on charge coupled devices, or charge.injection devices may also be of interest. Typical of the families of detectors, the Reticon detectors are built in a number of elements/array sizes. Commercially available units have anywhere from 128 to 1024 elements/array. Each individual element in the array is 1 x 1 mil to 1 x 100 mil in area, and are spaced on approximately 1 mil centers. The spectrometer system discussed in this article was built using Reticon-type devices. 

The first detectors to be used in OMA systems were standard TV image tubes. These were silicon vidicons or the more sensitive Silicon Intensified Target (SIT) detectors, which both employed silicon targets to convert optical information into electronic form. More recently, the use of solid state detectors in the form of a diode array (Reticon) has been found to have some advantages over the vidicons and SIT tubes. Current developments in the field of charge coupled devices (CCD) will probably soon provide an even better multielement detector for use in OMA systems. 

Charge coupled device (CCD) A solid-state two-dimensional detector array used for spectroscopy and imaging. Charge-injection device (CID) A solid-state photodetector array used in spectroscopy. 

A wide variety of solid-state detectors consisting of multiple elements (multiple channels) have been developed over the past 20 years (140). Devices that fall into this category include silicon photodiode (SPD) arrays, charge injection devices (CID), charge coupled devices (CCD), microchannel plate (MCP) image inten-... 

Silicon charge coupled devices (CCDs), commonly used in solid-state video cameras and in research applications, are being applied to low light level spectroscopy applications. The main advantage of area array CCDs over linear photodiode detectors is the two-dimensional format, which provides simultaneous measurements of spatial and spectral data. 

The common detector for AAS is the photomultiplier tube (PMT). The construction and operation of a PMT has been described in Chapter 5. While PMTs are the most common detectors, solid-state single and multichannel detectors such as photodiode arrays (PDAs) (discussed in Chapter 5) and charge-coupled devices (CCDs) (discussed in Chapters 5 and 7) are increasingly being nsed in AAS spectrometers. Many small systems, particularly those dedicated to one element snch as a dedicated CVAAS mercury analyzer, use solid-state detectors instead of PMTs. Multielement simnltaneous AAS systems also use multichannel solid-state detectors to measure more than one wavelength at a time. 

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