Cadmium zinc telluride

Grooves 5 are formed in a substrate 1 of either cadmium telluride, cadmium zinc telluride, gallium arsenic, silicon or sapphire. A layer 4 of Hgi.yCd,Te is formed at the bottom and at the sides of the grooves. Next, the whole structure is covered by a p-type Hgi.xCd,Te layer (y < x), in which n-type regions 3 are formed. 

Lan, C. W. (2005), Flow and segregation control by accelerated rotation for vertical Bridgman growth of cadmium zinc telluride ACRT versus vibration, J. Crystal Growth, 274 (3-4), 379-386. 

Solid-state detectors directly convert the absorbed gamma ray energy into collection of electric charge and do not need photomultiplier tubes. Since the PMT is a bulky and expensive component, this represents a significant breakthrough. Cadmium zinc telluride is an attractive solid-state detec-... 

The other potential semiconductor detector materials have a larger band gap than germanium and consequently would have the advantage of room temperature operation assuming that their other properties were satisfactory. Of these, only cadmium telluride, cadmium zinc telluride (CZT) and mercuric iodide have found their way into... 

CdZnTe Cadmium Zinc Telluride. As CdTe above, with some superior characteristics. 

Franks, R.B. James, 2001, Cadmium zinc telluride and its use as a nuclear radiation detector material . 

Mercury Telluride. Compounds of mercury with tellurium have gained importance as semiconductors with appHcations in infrared detection (9) and solar cells (10). The ratio of the components is varied, and other elements such as cadmium, zinc, and indium are added to modify the electronic characteristics. 

Commonly used II-VI compounds include zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium telluride, and mercury cadmium telluride. These materials are not as widely used as the III-V compounds, one reason being that it is difficult to achieve p-type doping. Mercury cadmium telluride is used extensively in military night sights, which detect in the 8-13 im spectral band (a similar material, platinum silicide, is being developed for that purpose). The major applications ofCVD II-VI compounds are found in photovoltaic and electroluminescent displays. 

Zinc telluride, ZnTe, was deposited on quartz, silicon, InAs, and GaSb substrates using Zn[TeSi(SiMe3)3]2 at temperatures between 250 °C and 350 °C. On InAs (orientation not specified) a cubic ZnTe layer was obtained. Problems of stoichiometry are encountered at temperatures below 325 °C because decomposition of the precursor is incomplete, while at higher temperatures (above 350 °C) the deposited ZnTe decomposes into Zn (which evaporates) and involatile elemental tellurium which remains. The results with the analogous cadmium precursor (1.4 torr, 290 °C) indicate that the CdTe films may be of better stoichiometry than those of ZnTe, with XRD results indicating that on a Si substrate the hexagonal phase is predominantly... 

Operating wavelength of the detector should be as close to the cutoff wavelength (Ico = hc/Eg) as possible. This requirement is easiest to meet in three-compound semiconductor materials with continually adjustable bandgap, e.g., mercury cadmium telluride (Hgi- cCd cTe) [8], mercury zinc telluride (Hgi- cZn cTe) [69-71], lead tin telluride Pbi Sn Te [72, 73], and indium arsenide antimonide (Ini - cAS cSb) [74] which for x = 0 reduces to indium antimonide, InSb. 

Abrasion and corrosion protection for germanium, magnesium fluoride, cadmium telluride, zinc sulfide, and zinc selenide IR windows. 

It reacts rather violently with numerous metals. With molten sodium, the reaction is strong. With potassium, the mixture incandesces but, if a large quantity of potassium in excess is used, there is deflagration. With zinc, cadmium and tin, there is incandescence. In the latter case, tin telluride, SnTe, forms. 

The next five chapters deal with deposition of specific groups of semiconductors. In Chapter 4, II-VI Semiconductors, all the sulphides, selenides, and (what little there is on) tellurides of cadmium (most of the chapter), zinc (a substantial part), and mercury (a small part). (Oxides are left to a later chapter.) This chapter is, understandably, a large one, due mainly to the large amount of work carried out on CdS and to a lesser extent on CdSe. Chapter 5, PbS and PbSe, provides a separate forum for PbS and PbSe, which provided much of the focus for CD in earlier years. The remaining sulphides and selenides are covered in Chapter 6, Other Sulphides and Selenides. There are many of these compounds, thus, this is a correspondingly large chapter. Chapter 7, Oxides and Other Semiconductors, is devoted mainly to oxides and some hydroxides, as well as to miscellaneous semiconductors that have only been scantily studied (elemental selenium and silver halides). These previous chapters have been limited to binary semiconductors, made up of two elements (with the exception of elemental Se). Chapter 8, Ternary Semiconductors, extends this list to semiconductors composed of three elements, whether two different metals (most of the studies) or two different chalcogens. 

Consequently, the bond is fully saturated for A sp = 0 with a bond order of 1, but it is only partially saturated by the time the gap closes for AEap/2 h = 1 (cf eqn (7.92)) when the bond order equals 0.76. This simple second moment model has been extended to include the compound semiconductors. The resultant values of the bond order are given in Table 7.2. We see that the bonds in tetrahedral carbon and silicon are almost fully saturated, but those in zinc selenide and cadmium telluride are only about 75% saturated due partly to the mismatch in the sp orbitals between chemically distinct atoms. 

In a recent synthesis of a mixed zinc/cadmium telluride alloy, a mixture of dimethyl-cadmium and diethylzinc was employed. The original authors interpreted the results by assuming that the redistribution reaction 3 is essentially thermoneutral since the difference between the enthalpies of formation for the symmetrical dialkylzincs is small. 

Another exciting thin-film company is FirstSolar (www.firstsolar.com). First Solar claimed to achieve a manufacturing cost of only 1.08 per watt during the third quarter of 2008. The company uses cadmium telluride as a semiconducting material, which is a byproduct of the mining and production of base metals such as zinc and copper. First Solar has entered into many excellent long-term sales agreements with major electric utility companies. 

In a simple transmission experiment the liquid sample is examined in a cell made of a suitable infrared transparent medium. These include sodium chloride, potassium bromide, zinc selenide, cadmium telluride, and germanium. Materials like sodium chloride should not be used to study solutions in protic solvents like methanol and water. 

Antimony is also used as a dopant in -type semiconductors. It is a common additive in dopants for silicon crystals with impurities, to alter the electrical conductivity. Interesting semiconductor properties have been reported for cadmium antimonide [12050-27-0], CdSb, and zinc antimonide [12059-55-9], ZnSb. The latter has good thermoelectric properties. Antimony with a purity as low as 99.9+% is an important alloying ingredient in the bismuth telluride [1504-82-1], Bi Te class of alloys which are used for thermoelectric cooling. 

The hosts that we have discussed to date have been ionic in nature, and dielectric as well (they are non-conductive). There is also another class of phosphor hosts which are covalent and semi-conductive in nature, namely the zinc and cadmium sulfides and/or selenides. The criterion for selection of a semi-conducting host for use as a phosphor includes choice of a composition with an energy band gap of at least 3.00 ev. This mandates the use of an optically inactive cation, combined with sulfide, selenide and possibly telluride. The ojq gen-dominated groupings such as phosphate, or silicate or arsenate, etc. are not semi-conductive in nature. And, none of the other transition metal sulfides have band gaps sufficiently... 

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