Metal organic vapor-phase deposition

Cyclopentadienyl compounds have been thoroughly investigated as suitable precursors to rare earth doped semiconductors in MOCVD (metal-organic chemical vapor deposition) or MOVPE (metal-organic vapor phase epitaxy) processes [283]. The use of btsa complexes for the same purpose has appeared in the literature very recently [285]. Typical process conditions are shown in Scheme 14. It was found that the carbon contamination of the deposited metal is less in the btsa case. 

D nanoribbons and nanowires of different metal-containing Pcs have also been prepared by organic vapor-phase deposition (OVPD), a technique used to fabricate organic millimeter-sized crystals, thin films, or nanostructures [211], Scanning electron microscopy (SEM), TEM, x-ray diffraction (XRD), and absorption measurement studies have revealed that the morphology of the nanostructures was strongly dependent on the chemical nature of the deposited macrocycle, the nature and the temperature of the substrate, and the source-to-substrate distance. 

Metal-organic vapor-phase epitaxy the same as MOCVD, but implying specific induced crystalline orientation of the deposited film... 

The methods available for preparation of the different layers in thin-film solar cells include physical methods such as vacuum sputtering, vapor-phase deposition, and molecular beam epitaxy as well as chemical methods such as chemical vapor-phase deposition, metal organic vapor-phase epitaxy, chemical bath deposition (CBD), and electrochemical deposition (ED). This chapter explores the potential of electrodeposition as a route to the fabrication of absorber layers such as CdTe, CIGS, and CZTS for thin-film solar cells. Electrochemistry may also be usefiil for the preparation of transparent layers such as ZnO this topic has been reviewed by Pauporte and lincot [13]. 

Electrodeposition of semiconductors is a low-cost process. The most expensive equipment used in the process is a computerized potentiostat which may cost up to 5,000 compared to techniques like molecular beam epitaxy (MBE) or metal organic vapor phase epitaxy (MOVPE) in which the cost of the machines is in the order of 1 million. In addition, electrodeposition is versatile in application in the sense that many semiconductor materials can be electrodeposited using the same equipment. The only change required is basically the replacement of the deposition electrolyte by the desired one at any time. Evidence of a variety of electrodeposited semiconductors includes CdTe [32-42], CdS [10,32], ZnSe [11], ZnTe [12-14], SnS [17], CuInSea [18-22], CuInGaSe2 [23-27], and nitrides [9,43]. 

Although first deposition experiments of nonpolar GaN films on r-plane sapphire were performed as early as in 1987 [5], the defect structure in wurtzite GaN and related compounds has been mainly studied in the past focusing on films oriented along the hexagonal [0001] axis (c-axis). Growth techniques such as molecular beam epitaxy (MBE) [1], metal organic vapor phase epitaxy (MOVPE) [6], and hydride vapor phase epitaxy (HVPE) [7,8] are established for polar as well as nonpolar GaN growth. The structural quality of a-plane GaN... 

The detector arrays are processed on 2 in. or 3 in. diameter PACE-I material. The PACE-I material fabrication process has been described extensively elsewhere (Gertner et al. 1983). In summary, metal-organic vapor phase epitaxy (MOVPE) CdTe is deposited onto properly polished sapphire. 

Metastable alloys have been deposited as epitaxial thin films on a variety of substrates by a variety of techniques. Deposition methods (see Chapters 10-12) have included sputtering, metal-organic vapor-phase epitaxy (MOVPE), molecular beam... 

Organoindium substances are important, especially for the production of materials by metal-organic chemical vapor-phase deposition (MOCVD). This technique involves the thermal decomposition of mixtures of an organoindium compound and a compound such as phosphine (PH3), leading to the deposition of ordered layers of InP. The resulting compound can be used in the formation of semiconductors and solid-state optical devices (similar to silicon), see also Inorganic Chemistry. 

Several techniques have been reported and, at the present time, the vapor phase deposition processes operating at temperatures around 300 °C are the most used. Thus II-VI compounds films like CdS, CdSe, CdTe, ZnS, ZnSe, and ZnTe have been grown epitaxially on Si, InP, GaAs, GaP, by molecular beam epitaxy (MBE) [204-207], by metal organic chemical vapor deposition (MOCVD) [208-210], or by pulsed laser deposition [211, 212]. Epitaxial deposition from aqueous solutions at low temperatures (< 100 °C) represents another approach. Specific beneficial effects may be also expected due to the simplicity of the process involving low cost investments. On the other hand the low temperature has for consequence the absence of interdiffusion processes around interfaces and the interfacial properties of the solids in contacts with solutions implicate excellent coverage properties at low thicknesses. Different... 

Although Manasevit coined the term metal organic chemical vapor deposition (MOCVD) about a quarter of a century ago [6], the basic reactions were known to chemists at least a decade earlier. Strictly defined, MOCVD refers only to those CVD processes which result in thin film growth from a set of precursors possessing metal-carbon bonds. Since this requirement is not met rigorously in many real world systems, CVD is employed as a generic term for all chemically-based vapor phase deposition processes. 

Synthesis mefliods of NWs basically include both vapor phase and solution techniques. Compared to physical methods such as nanohthography and other patterning techniques, chemical methods have been more versatile and effective in the synthesis of these nanowires. The chemical synthesis includes various methods thermal evaporation, chemical vapor-phase deposition, metal-organic chemical... 

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