Semiconductor detectors

Kind of radiation Ionization chambers Proportional counters Geiger-Muller counters Scintillation detectors Semiconductor detectors... 

Like scintillation detectors, semiconductor detectors are usually used in gamma spectrometer set-ups to identify radionuclides and determine their activities in a sample. A semiconductor detector is much more expensive and somewhat more troublesome to operate than a scintillation detector, but it can distinguish much better between different radiation energies and is better for nuclide identification. 

Use Ceramics, infrared radiation detector, semiconductor, ceramic glaze, source of lead. 

For bulk semiconductors and multiple quantum well structures (one-dimensional confined semiconductors), transport properties are of great interest and are important for practical applications such as transistors and detectors. Semiconductor nanoclusters are usually confined in three-dimensions by insulating matrices such as polymers and glasses, where the transport of carriers is not feasible. To explore transport-related applications of semiconductor clusters, a matrix that is capable of transporting carriers is needed, In addition, the redox properties of the matrix have to allow injection of carriers from semiconductor nanoclusters to the matrix. 

Effect of density and size of detector material. The efficiency of a detector will increase if the probability of an interaction between the incident radiation and the material of which the detector is made increases. That probability increases with detector size. But larger size is of limited usefulness because the background increases proportionally with the size of the detector, and because in some cases it is practically impossible to make large detectors. (Semiconductor detectors are a prime example.)... 

The quantitative determination of X-ray intensities with a photon energy up to 150 keV can be realized by three types of detectors semiconductor-based detectors which call for efficient cooling, ionization chambers which have a low quantum detection efficiency (< 50%), and detectors based on luminescent materials. The latter type of detector is of interest here, because it is realized by the combination of a luminescent material with a photodiode. 

There are three major classes of X-ray detectors in commercial use gas-filled detectors, scintillation detectors, and semiconductor detectors. Semiconductor detectors will be discussed with EDXRF equipment. Both WDXRF and EDXRF detection makes use of a signal processor called a pulse height analyzer or selector in conjunction with the detector, and discussed subsequently. 

The motivation to produce transistors and integrated circuits led to improvements in semiconductor materials, which led to improved detectors. Semiconductors might be considered... 

B. Infrared photon detectors (semiconductors such as InAs, InSb, PbS, and PbSe)... 

GeIger-Mueller tubes scintillation detectors semiconductor detectors... 

The war itself also drove the development of improved and miniaturised electronic components for creating oscillators and amplifiers and, ultimately, semiconductors, which made practical the electronic systems needed in portable eddy current test instruments. The refinement of those systems continues to the present day and advances continue to be triggered by performance improvements of components and systems. In the same way that today s pocket calculator outperforms the large, hot room full of intercormected thermionic valves that I first saw in the 50 s, so it is with eddy current instrumentation. Today s handheld eddy current inspection instrument is a powerful tool which has the capability needed in a crack detector, corrosion detector, metal sorter, conductivity meter, coating thickness meter and so on. 

For the parallel recording of EEL spectra in STEM, linear arrays of semiconductor detectors are used. Such detectors convert the incident electrons mto photons, using additional fluorescent coatings or scintillators in the very same way as the TEM detectors described above. 

By inserting a semiconductor x-ray detector into the analysis chamber, one can measure particle induced x-rays. The cross section for particle induced x-ray emission (PIXE) is much greater than that for Rutherford backscattering and PIXE is a fast and convenient method for measuring the identity of atomic species within... 

Thermocouples, bolometers and pyroelectric and semiconductor detectors are also used. The first three are basically resistance thermometers. A semiconductor detector counts photons falling on it by measuring the change in conductivity due to electrons being excited from fhe valence band info fhe conduction band. 

Figure 8.28 shows how the X-rays fall on the solid or liquid sample which then emits X-ray fluorescence in the region 0.2-20 A. The fluorescence is dispersed by a flat crystal, often of lithium fluoride, which acts as a diffraction grating (rather like the quartz crystal in the X-ray monochromator in Figure 8.3). The fluorescence may be detected by a scintillation counter, a semiconductor detector or a gas flow proportional detector in which the X-rays ionize a gas such as argon and the resulting ions are counted.

Fig. 1. Photoexcitation modes iu a semiconductor having band gap energy, E, and impurity states, E. The photon energy must be sufficient to release an electron (° ) iato the conduction band (CB) or a hole (o) iato the valence band (VB) (a) an intrinsic detector (b) and (c) extrinsic donor and acceptor...

---