Lattice gallium compounds

Generally speaking most of the shallow impurity levels which we shall encounter are based on substitution by an impurity atom for one of the host atoms. An atom must also occupy an interstitial site to be a shallow impurity. In fact, interstitial lithium in silicon has been reported to act as a shallow donor level. All of the impurities associated with shallow impurity levels are not always located at the substitutional sites, but a part of the impurities are at interstitial sites. Indeed, about 90% of group-VA elements and boron implanted into Si almost certainly take up substitutional sites i.e., they replace atoms of the host lattice, but the remaining atoms of 10% are at interstitial sites. About 30% of the implanted atoms of group-IIIA elements except boron are located at either a substitutional site or an interstitial site, and the other 40% atoms exist at unspecified sites in Si [3]. The location of the impurity atoms in the semiconductors substitutional, interstitial, or other site, is a matter of considerable concern to us, because the electric property depends on whether they are at the substitutional, interstitial, or other sites. The number of possible impurity configurations is doubled when we consider even substitutional impurities in a compound semiconductor such as ZnO and gallium arsenide instead of an elemental semiconductor such as Si [4],... 

According to Dzurus and Hennig 15) the free chlorine necessary for the occurrence of reaction between graphite and aluminum trichloride does not act catalytically, as Riidorff and Zeller first assumed, but is partly taken up in the lattice. Riidorff and Landel 61) found this to be true of the gallium trichloride-graphite compound also. For both compounds the ratio Me Cl is between 1 3.2 and 1 3.4 and the compounds therefore oxidize potassium iodide solution and cause iodine to separate. 

The sulphides M2S3 are all made by direct combination of the elements. But GaS is also known and has an unusual layer lattice containing Ga2 ions (Hahn and Frank, 1955). The nitride GaN,unreactive to water and acids, is made by heating gallium in ammonia at 1000° the corresponding indium compound is best made by heating (NH4)3lnFg. Both have the wurtzite lattice. 

The compounds R3MC and RM3C3 are the only known compositions that exist in the rare-earth-metal-(aluminium, gallium, indium and thallium)-carbon systems at the present time. A number of reports on the preparation of cubic perovskite-type carbides containing rare earth elements with the general formula RjMC 00 (Jeitschko et al. 1964, Rosen and Sprang 1965, Haschke et al. 1966a, b, Nowotny 1968) contain little information about their properties other than their lattice parameters. 

The x-ray diffraction method was used to determine the squares of the structure amplitudes of gallium phosphide, the atomic scatterii factors of the gallium and phosphorus ions in this compound, and the distribution of the electron density in the lattice along the [111] direction. 

Figure 4.3 Shows the crystal structures of three compounds used in microelectronics. Each has a different Bravais lattice. To see the Bravais lattices of each compound, look only at the aluminum, strontium, and gallium atoms, respectively.

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