Gallium arsenide deposition

Villegas, I. Stickney, J. L. 1992. Preliminary studies of gallium arsenide deposition on gold (100), (110), and (111) surfaces by electrochemical atomic layer epitaxy. J. Electrochem. Soc. 139 686-94. 

Monolayers can be transferred onto many different substrates. Most LB depositions have been perfonned onto hydrophilic substrates, where monolayers are transferred when pulling tire substrate out from tire subphase. Transparent hydrophilic substrates such as glass [18,19] or quartz [20] allow spectra to be recorded in transmission mode. Examples of otlier hydrophilic substrates are aluminium [21, 22, 23 and 24], cliromium [9, 25] or tin [26], all in their oxidized state. The substrate most often used today is silicon wafer. Gold does not establish an oxide layer and is tlierefore used chiefly for reflection studies. Also used are silver [27], gallium arsenide [27, 28] or cadmium telluride wafer [28] following special treatment. 

A schematic of epitaxial growth is shown in Fig. 2.11. As an example, it is possible to grow gallium arsenide epitaxially on silicon since the lattice parameters of the two materials are similar. On the other hand, deposition of indium phosphide on silicon is not possible since the lattice mismatch is 8%, which is too high. A solution is to use an intermediate buffer layer of gallium arsenide between the silicon and the indium phosphide. The lattice parameters of common semiconductor materials are shown in Fig. 2.12. 

Gallium arsenide is epitaxially deposited on a silicon substrate and the resulting composite combines the mechanical and thermal properties of silicon with the photonic capabilities and fast electronics of gallium arsenide. 

Manasevit A process for making electronic devices by depositing thin films of elements or simple compounds such as gallium arsenide on flat substrates by CVD from volatile compounds such as trimethyl gallium and arsine. 

In one method, arsenic(III) chloride (AsCf, boiling temperature 376 K) is used to transport gallium vapour to the reaction site where gallium arsenide is deposited in layers. The reaction involved is ... 

The trimethylamine adduct of aluminum hydride (alane) has been of recent interest as a precursor for the chemical vapor deposition (CVD) of aluminum metal1 and aluminum gallium arsenide thin films.2 Because of the absence of aluminum-carbon covalent bonds in the precursor, carbon incorporation in the resulting films can be suppressed significantly. In addition, the deposition temperature can be lowered. 

Fig. 9. A Schottky barrier gate used in the metal-semiconductor field-effect transistor (MESFET) in AT T gallium arsenide microchips. The tiny gate is only one micrometer wide (1/25,400 inch). The gate electrode is deposited before the ion-implantation process so that the gate material will shade the channel under it from the ion rain that doses the exposed material. (AT T Technology)...

Fig. 5 Indium arsenide quantum dots deposited on gallium arsenide by OMVPE. Photo courtesy of Jeff Cederberg and R. M. Biefeld, Sandia National Laboratories.

The last class of CVD reaction is what we will call co-deposition. This indicates deposition from a mixture of precursors, where atoms from several species contribute to the deposited film. This approach is generally used for the deposition of compound materials, where the desired film is composed of several elements. Examples of this kind of CVD system include the deposition of gallium arsenide from trimethylgallium (TMG) and arsine Ga(CH3)3 + ASH3 GaAs + 3 CH, as well as the deposition of silicon nitride from silicon... 

Another example of phase change during reaction is chemical vapor deposition (CVD), a process used to manufacture microelectronic materials. Here, gas-phase reactants are deposited (analogous to condensation) as thin films on solid surfaces (see Problem P3-25). One such reaction is the production of gallium arsenide, which is used in computer chips. 

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