Vapor growth method

A CdTe layer 12 is formed over the structure by the use of a vapor growth method. Thereafter, an HgCdTe layer 14 is formed over the CdTe layer. 

The advantages of vapor growth methods can be summarized as follows ... 

Epitaxial crystal growth methods such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) have advanced to the point that active regions of essentially arbitrary thicknesses can be prepared (see Thin films, film deposition techniques). Most semiconductors used for lasers are cubic crystals where the lattice constant, the dimension of the cube, is equal to two atomic plane distances. When the thickness of this layer is reduced to dimensions on the order of 0.01 )J.m, between 20 and 30 atomic plane distances, quantum mechanics is needed for an accurate description of the confined carrier energies (11). Such layers are called quantum wells and the lasers containing such layers in their active regions are known as quantum well lasers (12). 

The most important nanomaterial synthesis methods include nanolithography techniques, template-directed syntheses, vapor-phase methods, vapor-liquid-solid (VLS) methods, solution-liquid-solid (SLS) approaches, sol-gel processes, micelle, vapor deposition, solvothermal methods, and pyrolysis methods [1, 2]. For many of these procedures, the control of size and shape, the flexibility in the materials that can be synthesized, and the potential for scaling up, are the main limitations. In general, the understanding of the growth mechanism of any as-... 

Chapter 10 deals with composite films synthesized by the physical vapor deposition method. These films consist of dielectric matrix containing metal or semiconductor (M/SC) nanoparticles. The film structure is considered and discussed in relation to the mechanism of their formation. Some models of nucleation and growth of M/SC nanoparticles in dielectric matrix are presented. The properties of films including dark and photo-induced conductivity, conductometric sensor properties, dielectric characteristics, and catalytic activity as well as their dependence on film structure are discussed. There is special focus on the physical and chemical effects caused by the interaction of M/SC nanoparticles with the environment and charge transfer between nanoparticles in the matrix. 

A CdTe layer 12 is formed on a sapphire substrate 11. An insulating film 13 is formed at regions not corresponding to the detector elements. An isothermal vapor phase growth method is used to convert regions 16 corresponding to the detector elements. 

Chemical vapor deposition method is used as an alternative to circumvent the limitations of the other synthetic methods. In chemical vapor deposition method, a substrate is prepared with a layer of metal catalyst particles, most commonly nickel, cobalt, iron, or a combination of these materials. The diameter of the grown nanotubes is related to the size of the metal particles. The substrate is heated to approximately 700°C. To initiate the growth of nanotubes, two gases are bled into the reactor a process gas (such as ammonia, nitrogen, hydrogen, etc.) and... 

Lee, C. J., et al. (2002), Large-scale production of aligned carbon nanotubes by the vapor phase growth method, Chem. Phys. Lett., 359(1-2), 109-114. 

Miller, T. Y., He, X.M., Carter, D.C., A comparison between protein crystals grown with vapor diffusion methods in microgravity and protein crystals using a gel liquid liquid diffusion ground-based method. J. Cryst. Growth 1992, 122 (1-4), 306-309. 

Carlson, E.E., The growth of HgS and Hg3S2Cl2 single crystals by a vapor phase method, J. Cryst. Growth, 1, 271-277 (1967). 

For their rich potential in various applications described in the previous section, the synthesis and assembly of various ZnO micro and nanostructures have been extensively explored using both gas-phase and solution-based approaches. The most commonly used gas-phase growth approaches for synthesizing ZnO structures at the nanometer and micrometer scale include physical vapor deposition (40, 41), pulsed laser deposition (42), chemical vapor deposition (43), metal-organic chemical vapor deposition (44), vapor-liquid-solid epitaxial mechanisms (24, 28, 29, 45), and epitaxial electrodeposition (46). In solution-based synthesis approaches, growth methods such as hydrothermal decomposition processes (47, 48) and homogeneous precipitation of ZnO in aqueous solutions (49-51) were pursued. 

Similarly, impervious yttria-stabilized zirconia membranes doped with titania have been prepared by the electrochemical vapor deposition method [Hazbun, 1988]. Zirconium, yttrium and titanium chlorides in vapor form react with oxygen on the heated surface of a porous support tube in a reaction chamber at 1,100 to 1,300 C under controlled conditions. Membranes with a thickness of 2 to 60 pm have been made this way. The dopant, titania, is added to increase electron How of the resultant membrane and can be tailored to achieve the desired balance between ionic and electronic conductivity. Brinkman and Burggraaf [1995] also used electrochemical vapor deposition to grow thin, dense layers of zirconia/yttria/terbia membranes on porous ceramic supports. Depending on the deposition temperature, the growth of the membrane layer is limited by the bulk electrochemical transport or pore diffusion. 

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