Substrates indium

N-type layers are formed in recessed regions formed in a p-type HgCdTe substrate. Indium bumps 16 are formed in the recessed regions and on corresponding input regions of a silicon substrate 17. The two substrates are joined in a flip-chip process in which the corresponding bumps will meet in the recessed regions. 

The Langmuir-Blodgett (LB) technique has been employed to prepare membranes with well-defined molecular packing. Octadecylamine was selected as an amphiphile which forms chaiged mono-layers on the water surface and has good insulating properties when deposited onto electrically conductive substrates, indium-tin oxide (ITO) layer. 

Both ends of each wire are stripped and one end is soldered onto the outer edge of the uncoated conductive part of the substrate. Indium solder is often a good choice for soldering the lead wires to the substrate due to its high conductivity and good adhesion to surfaces. For better adhesion, a thin layer of indium can be deposited first onto the substrate (Fig. 3.1b). Next, more indium is used to attach the wires onto the substrate (Fig. 3.1c). Alternatively, silver paint can be used, in which case the sample should dry in air for a few hours or annealed at 80 °C for 20-30 min. 

The solder and ahoy market, including low melting or fusible ahoys, is a principal user of indium (see SoLDERS AND BRAZING ALLOYS). The addition of indium results in unique properties of solders such as improved corrosion and fatigue resistance, increased hardness, and compatibhity with gold substrates. To fachitate use in various appHcations, indium and its ahoys can be easily fabricated into wine, ribbon, foil, spheres, preforms, solder paste, and powder. 

AppHcations for electroplated indium coatings include indium bump bonding for shicon semiconductor die attachment to packaging substrates and miscehaneous appHcations where the physical or chemical properties of indium metal are desired as a plated deposit. 

StiU another method used to produce PV cells is provided by thin-fiLm technologies. Thin films ate made by depositing semiconductor materials on a sohd substrate such as glass or metal sheet. Among the wide variety of thin-fiLm materials under development ate amorphous siUcon, polycrystaUine sUicon, copper indium diselenide, and cadmium teUuride. Additionally, development of multijunction thin-film PV cells is being explored. These cells use multiple layers of thin-film sUicon alloys or other semiconductors tailored to respond to specific portions of the light spectmm. 

Spray Pyrolysis. In spray pyrolysis, a chemical solution is sprayed on a hot surface where it is pyrolyzed (decomposed) to give thin films of either elements or, more commonly, compounds (22). Eor example, to deposit CdS, a solution of CdCl plus NH2CSNH2 (thiourea) is sprayed on a hot surface. To deposit Iu202, InCl is dissolved in a solvent and sprayed on a hot surface in air. Materials that can be deposited by spray pyrolysis include electrically conductive tin—oxide and indium/tin oxide (ITO), CdS, Cu—InSe2, and CdSe. Spray pyrolysis is an inexpensive deposition process and can be used on large-area substrates. 

Figure 9-3. Conventional multilayer light emission device (LED) indium tin oxide (ITO) electrode on a substrate, active layers A (hole transport), B (emitter), C (electron transport), and a niclat electrode. A possible encapsulation layer has been omitted, which would prevent the conjugated molecules from photo-oxidation.

A procedure involving (a) the deposition of nearly stoichiometric films of copper and indium on suitable substrates using vacuum evaporation or electrodeposition and (b) the heat treatment of Cu-In films in a hydrogen-selenium atmosphere at temperatures above 630 °C was reported to yield large grain (several mm in size), stoichiometric thin films of chalcopyrite CIS with a preferred 112 orientation [167]. 

Li KW, Meng XT, Liang X, Wang H, Yan H (2006) Electrodeposition and characterization of PbSe films on indium tin oxide glass substrates. J Solid State Electrochem 10 48-53... 

Reductive coupling of aldimines obtained from aromatic aldehydes and aromatic amines to generate vicinal diamines mediated by indium was carried out in aqueous ethanol (Eq. 11.59)." Small indium rods were used in this study. No side-product was observed due to unimolecular reduction. The presence of NH4CI was found to accelerate the reaction. The reaction fails completely in CH3CN, DMF, or wet DMF. The use of nonaromatic substrates also resulted in the failure of the reaction. 

In two independent studies, InP was grown from the precursor complex [(CH3)2In /i-P(But)2 ]2.255 256 262 First, Cowley et al. employed the use of a cold-wall reactor to deposit InP using H2 or He as the carrier gas, with substrate temperatures between 450 °C and 700 °C. Using an MBE reactor, Bradley and co-workers found that stoichiometric growth was only possible at 480 °C and only when a simultaneous secondary incident flux of dissociated phosphine was added. Lower growth temperatures resulted in indium-rich deposits. 

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