Amorphous solids germanium

Phenylgermanic acid anhydride, (CgHsGeOjaO.—Equimolecular proportions of mercury diphenyl and germanium tetrachloride in dry xylene are heated in a sealed Pyrex bulb for two days, then diluted with dry ether and filtered. The solid residue is pure phenylmercuric chloride, and the filtrate is treated with benzene, and finally with water containing a few drops of ammonium hydroxide. The granular precipitate which separates at the liquid interface is removed and dried at 115° C. The anhydride is a white, fluffy, amorphous solid, with no definite melting-point, soluble in excess of alkali, and reprecipitated by carbon dioxide, insoluble in water and organic solvents. 

Figure 20 Raman spectra obtained from a-Geo.o4Co96 films annealed at several temperatures. The solid line is the fitted spectrum, as discussed in the text. The D and G bands are also plotted (dashed lines) [57]. (Reprodueed from Diamond and Related Materials, 8, Mariotto, G., et al., Raman spectroscopy and scanning electron microscopy investigation of annealed amorphous carbon germanium films deposited by d.c. magnetron scattering, pp. 668-672. Copyright 1999, with permission from Elsevier Science.)...

As there are no suitable organometallic precursors commercially available, initial work dealt with the synthesis of such a precursor [4]. 2,5-Bis(rbutyl)-2,5-diaza-l-germa-cyclopentane is a monomeric solid with a melting point of 45 °C and a sufficient vapour pressure of 0.40 mbar at 40 °C to allow its introduction into the CVD reactor. For the details about the synthesis and properties of this precursor we refer to a recent paper [4]. The present work deals with the investigation of the thermal decomposition of the precursor, the deposition of amorphous germanium (a-Ge) and the characterization of the deposited thin films. Finally some data should try to give some understanding about the deposition mechanism. 

Ikeda T, Kobayashi T, Takata M, Takayama T, Sakata M (1998) Charge density distributions of strontium titanate obtained by the maximum entropy method. Solid State Ion 108 151-157 Imai M, Mitamura T, Yaoita K, Tsuji K (1996) Pressure-induced phase transition of crystalline and amorphous silicon and germanium at low temperatures. High Pressure Res 15 167-189... 

Sayers DE, Hesterberg D, Zhou W, Robarge WP, Plummer GM (1997) XAFS characterization of copper contamination in the unsaturated and saturated zones of a soil profile. J de Physique IV 7 (Colloque C2, X-Ray Absorption Fine Structure, Vol. 2) 831-832 Sayers DE, Lytle FW, Stem EA (1972) Structure determination of amorphous germanium, germanium oxide, and germanium selenide by Fourier analysis of extended X-ray absorption fine structure (EXAFS). J Non-Crystal Solids 8-10 401-407... 

Fig. 6.4 Low temperature kj for various type I clathrates [35, 40-44], as well as data for amorphous Si02 dashed curve) and room temperature Kmin for elemental silicon and germanium (stars). The solid black line indicates a 1/...

This includes single crystal silicon [15], germanium [22] and alumina [10] fibers. Polycrystalline fibers can grow either by a VLS or a VS phase transformation when the incident laser power (focal temperature) is intermediate, and supports the growth of a fiber with a semisolid tip. This includes polycrystalline silicon [15], boron [5] and silicon carbide fibers [23]. Amorphous fibers are obtained by a VS phase transformation when the incident laser (focal temperature) is low, and supports the growth of a fiber with a hot but solid tip. This includes amorphous silicon [15], boron [12], carbon [13] [16], silicon carbide [23], and silicon nitride [17] fibers. 

J. Tauc, R. Grigorovici and A. Vancu, Optical properties and electronic structure of amorphous germanium, Physica Status Solid , 15(2), 627-637, 1966. 

---