Sulfide Cd

Four different types of junctions can be used to separate the charge carriers in solar cebs (/) a homojunction joins semiconductor materials of the same substance, eg, the homojunction of a p—n sibcon solar ceb separates two oppositely doped layers of sibcon 2) a heterojunction is formed between two dissimbar semiconductor substances, eg, copper sulfide, Cu S, and cadmium sulfide, CdS, in Cu S—CdS solar cebs (J) a Schottky junction is formed when a metal and semiconductor material are joined and (4) in a metal—insulator—semiconductor junction (MIS), a thin insulator layer, generaby less than 0.003-p.m thick, is sandwiched between a metal and semiconductor material. 

Cadmium Sulfide. CdS [1306-23-6] is dimorphic and exists ia the sphalerite (cubic) and wurtzite (hexagonal) crystal stmctures (40). At very high pressures it may exist also as a rock-salt stmcture type. It is oxidized to the sulfate, basic sulfate, and eventually the oxide on heating ia air to 700°C, especially ia the preseace of moisture (9). 

Light detectors fall into two categories photoconductors and photodetectors. Photoconductors are devices whose resistance decreases upon exposure to light. Cadmium sulfide (CdS) and cadmium selenide (CdSe) are the most commonly used photoconductor materials in the visible spectrum. They are still mostly produced by sputtering but CVD is used increasingly (see Ch. 12, Sec. 4.0). 

An instance of cadmium-zinc sulfide (Cd , Zni i S) cathodic electrodeposition can be found in the work of Morris and Vanderveen [130]. These researchers managed to obtain polycrystalline Cd , Zni i S films from stirred aqueous solutions (pH 2,... 

Ginley DS, Butler MA (1978) Flatband potential of cadmium sulfide (CdS) photoanodes and its dependence on surface ion effects. J Electrochem Soc 125 1968-1974... 

A prime contender for leading thin film technology as applied to solar cells is cadmium telluride (CdTe). Its bandgap is almost ideal for use as a solar cell for energy conversion from the Sun s spectrum. Here, CdTe and cadmium sulfide (CdS) are used to produce a low cost thin film solar cell... 

Figure 29.4 shows an example, the energy diagram of a cell where n-type cadmium sulfide CdS is used as a photoanode, a metal that is corrosion resistant and catalytically active is used as the (dark) cathode, and an alkaline solution with S and S2 ions between which the redox equilibrium S + 2e 2S exists is used as the electrolyte. In this system, equilibrium is practically established, not only at the metal-solution interface but also at the semiconductor-solution interface. Hence, in the dark, the electrochemical potentials of the electrons in all three phases are identical. 

Minerals dominated by cadmium are rare the sulfide CdS (greenockite), especially, is very rarely found. However, cadmium is widespread in zinc ores in low concentrations (0.2-0.4%) and is separated during processing of these ores and production of zinc. 

Many colored pigments are based on cadmium compounds. For instance, cadmium sulfide (CdS) and cadmium selenide (CdSe) are used as pigments when a durable, nonfading color is required. Red is produced by CdSe, and bright yellow is produced by CdS. 

Cadmium sulfide (CdS) is one of the most intriguing nonoxide semiconductors due to its sufficiently negative flat band potential (-0.66 V at pH 7) and optical absorption to 520 nm (bandgap = 2.4 eV), however it suffers from anodic... 

Cadmium sulfide (CdS), 2.4 eV bandgap, is one of the most widely studied non-oxide semiconductors. For a semiconductor irradiated by photons with energy equal to or greater than its bandgap, an electron from the valence band jumps to the conduction band leaving a positively charged hole behind in the valance band for CdS this is expressed as... 

The element combines with many nonmetals upon heating, forming its binary salts. It combines with halogens when heated, forming the corresponding halides. Heating with phosphorus, sulfur, and tellurium produces phosphide, CdsP2 sulfide, CdS and teUuride, CdTe salts, respectively. 

Matijevic and Wilhelmy (I) prepared uniform spherical polycrystalline particles of cadmium sulfide (CdS) by reaction of Cd2+ ions with thioacetamide (TAA) in a dilute acidic media (pH < 2), as shown in the TEM and SEM images of Figure... 

The reaction finished within 1 h at 26°C.. They used seed crystals of CdS to promote the uniformity of the final product, and analyzed the growth kinetics using Nielsen s chronomal. The isoelectric point in terms of pH was determined to be 3.7 by electrokinetic measurement. They also prepared zinc sulfide (ZnS polycrystalline spheres), whose isoelectric point in pH was 3.0 (2), lead sulfide (PbS monocrystalline cubic galena) (3), cadmium zinc sulfide (CdS/ZnS amorphous and crystalline spheres) (3), and cadmium lead sulfide (CdS/PbS crystalline polyhedra) (3), in a similar manner. 

Cadmium sulfide, CdS (Fig. 19), is, on the contrary, liable to intensive anodic photocorrosion in aqueous solutions, according to the equation... 

Sulfide and sulfoselenide pigments cadmium sulfoselenide cadmium sulfide (Cd, Zn) S ... 

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