Amorphous Hydrogenated Films

The thermal decomposition of silanes in the presence of hydrogen into siUcon for production of ultrapure, semiconductor-grade siUcon has become an important art, known as the Siemens process (13). A variety of process parameters, which usually include the introduction of hydrogen, have been studied. Silane can be used to deposit siUcon at temperatures below 1000°C (14). Dichlorosilane deposits siUcon at 1000—1150°C (15,16). Ttichlorosilane has been reported as a source for siUcon deposition at >1150° C (17). Tribromosilane is ordinarily a source for siUcon deposition at 600—800°C (18). Thin-film deposition of siUcon metal from silane and disilane takes place at temperatures as low as 640°C, but results in amorphous hydrogenated siUcon (19). 

Inorganic monomers can be used to plasma-deposit polymer-type films (16). At high plasma energies, the monomers are largely decomposed and can be used to form materials such as amorphous hydrogen-containing siUcon films from SiH for thin-film solar-ceU materials. 

A. J. Bevolo, M. L. Albers, H. R. Shanks, and J. Shinar. J. Appl. Phys. 62, 1240, 1987. VEELS in fixed-spot mode to depth profile hydrogen in amorphous silicon films to determine hydrogen mobility at elevated temperatures. 

Amorphous carbon films may be broadly classified as (i) amorphous carbon films, a-C films, deposited from carbon-containing gases with low or zero hydrogen content [72] and (ii) hydrogenated carbon films, a-C H films, formed from hydrocarbon-containing gases [73,74]. Both types of film contain different amounts of sp and sp bonded carbon. The amount of sp bonded carbon can be estimated from X-ray absorption near edge spectroscopy,... 

The classification of amorphous carbon films according to carbon bond type and hydrogen content can be represented in a triangular diagram, Fig. 6 [e.g., 70]. The comers at the base of the triangle correspond to graphite (100% sp carbon) and diamond (100% sp carbon). The apex represents 100% H, but the upper limit for formation of solid films is defined by the tie line between the compositions of polyethene, -(CH2) -, and polyethyne, -(CH) -. 

Koidl, R, Wild, Ch., Dischler, B., Wagner, J., and Ramsteiner, M., Plasma Deposition, Properties and Structure of Amorphous Hydrogenated Carbon Films, Mater. Sci. Forum, Vol. 

Selected Properties of Device Quality Hydrogenated Amorphous Silicon Films... 

Growth, Structure, and Properties of Plasma-Deposited Amorphous Hydrogenated Carbon-Nitrogen Films... 

In reality, several factors were mentioned as being responsible for this behavior, such as variations in bond angle distortion, in the internal stress or in the hydrogen content [40, 76], but all of them are also strongly correlated with the variation of optical gap width in amorphous carbon films. Theoretical work on Raman spectroscopy on DLC materials gave additional support for Dillon s interpretation [77]. 

Growth, Structure, and Properties of Plasma-Deposited Amorphous Hydrogenated Carbon-Nitrogen Films D. F. Franceschini, Institute de FIsica, Uni-versidade Federal Fluminense, Avenida Litoranea s/n, Niteroi, RJ, 24210-340, Brazil... 

A new, exciton-like mechanism has been proposed by Demidenko et al. [34] to describe the formation of amorphous NiP films. According to these authors, the electroless process is initiated by the reduction of Ni2 + by adsorbed hydrogen to produce clusters of pure Ni. Vacancy sites on these clusters capture a proton (presumably from the H2POJ anion) to form an exciton-like state, which subsequently captures more Ni atoms, and so on. Phosphorus can be captured and fixed at a vacancy site. 

In the early 1970s, Spear and coworkers (Spear, 1974 Le Comber et al., 1974), although unaware of the presence of hydrogen, demonstrated a substantial reduction in the density of gap states (with a corresponding improvement in the electronic transport properties) in amorphous silicon films that were deposited from the decomposition of silane (SiH4) in an rf glow discharge. 

Absorption characteristics, of hydrogenated amorphous silicon films, 22 133-134 Absorption coefficients, 23 126 Absorption-desorption towers, 10 614 Absorption maxima, vinylene shifts of,... 

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