Vapor deposition technologies

In recent years the coordination of N-, P-, or O-donor Lewis bases to aluminum and gallium trihydrides has been studied extensively (27). Interest in these complexes stems in part from their applications in a wide variety of areas, for example chemical vapor deposition technology (28) and organic synthesis (29). However, the corresponding carbene complexes of the heavier group 13 trihydrides have only been... 

The present availabihty of numerous types of solid electrolytes permits transport control of various kinds of mobile ionic species through those solid electrolytes in solid electrochemical cells, and permits electrochemical reactions to be carried out with the surrounding vapor phase to form products of interest. This interfacing of modem vapor deposition technology and solid state ionic technology has led to the recent development of polarized electrochemical vapor deposition (PEVD). PEVD has been applied to fabricate two types of solid state ionic devices, i.e., solid state potenfiometric sensors and solid oxide fuel cells. Investigations show that PEVD is the most suitable technique to improve the solid electrolyte/electrode contact and subsequently, the performance of these solid state ionic devices. 

Other pH-sensing transducers used in biosensors are metal oxide electrodes. Beside the common antimony oxide electrode, palladium oxide and iridium oxide probes have been coupled with immobilized enzymes. These sensors may be miniaturized by using chemical vapor deposition technology. Moreover, they are mechanically more stable than glass electrodes. Unfortunately the measuring signal of metal oxide electrodes is affected by redox active substances. 

Physical vapor deposition technology to produce membranes on a roll-in process and a metallic support is indicated by the authors as one of the more promising technology for such industrial mass production. 

An additional type of coating method frequently used is vapor deposition. Generally, this method involves deposition of the coating onto a substrate from the vapor phase. Vapor deposition technologies can be categorized into chemical vapor deposition (CVD) and physical vapor deposition (PVD). The two methods are distinct. 

Germanium difluoride can be prepared by reduction (2,4) of GeF by metallic germanium, by reaction (1) of stoichiometric amounts of Ge and HF in a sealed vessel at 225°C, by Ge powder and HgF2 (5), and by GeS and PbF2 (6). Gep2 has been used in plasma chemical vapor deposition of amorphous film (see Plasma TECHNOLOGY Thin films) (7). 

This article focuses primarily on the properties of the most extensively studied III—V and II—VI compound semiconductors and is presented in five sections (/) a brief summary of the physical (mechanical and electrical) properties of the 2incblende cubic semiconductors (2) a description of the metal organic chemical vapor deposition (MOCVD) process. MOCVD is the preferred technology for the commercial growth of most heteroepitaxial semiconductor material (J) the physics and (4) apphcations of electronic and photonic devices and (5) the fabrication process technology in use to create both electronic and photonic devices and circuits. 

Chemical Vapor Deposition. Chemical vapor deposition (CVD) of siHcon dioxide from tetraethoxysilane assisted by the presence of oxygen and a plasma is an important technology for the deposition of pure and modified dielectrics for microelectronics (61). An alternative method for the deposition of siHcon dioxide utili2es di-/-butoxydiacetoxysilane (62). 

In plasma chemical vapor deposition (PCVD), the starting materials are typically SiCl, O2, 2 6 GeCl (see Plasma technology). Plasma chemical vapor deposition is similar to MCVD in that the reactants are carried into a hoUow siUca tube, but PCVD uses a moving microwave cavity rather than a torch. The plasma formed inside the microwave cavity results in the deposition of a compact glass layer along the inner wall of the tube. The temperatures involved in PCVD are lower than those in MCVD, and no oxide soots are formed. Also, the PCVD method is not affected by the heat capacities or thermal conductivities of the deposits. 

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