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Amorphous Si1-xCx: H thin films were prepared by the rf magnetron sputtering method using a composite target of silicon and graphite. The dependence of the optical, structural, electrical, and optoelectronic properties on the carbon contentx was investigated, by measuring the optical absorption spectra, ir spectra, dark conductivity, photoconductivity and ESCA spectra. The optical gap was found to be unchanged with increasingx below about 0.6, in spite of the increase in the amount of the SiC bond. This is considered to be due to the formation of the carbon clusters. It is found that the photosensitivity shows a maximum at aboutx = 0.2, and is about one order of magnitude larger than the film withx = 0. This is related to the decrease in the dark conductivity, which is ascribed both to the formation of the SiC bond and to the reorganization of the defect-rich structure of sputter-deposited amorphous Si by the addition of about 20% carbon. The photoconductive effect was gradually lost in the range ofx above 0.6. In this range, the optical gap increases rapidly owing to the rapid increase of the SiC bond.

Amorphous Si1-xCx:H films have been prepared by the r.f. magnetron sputtering method using a silicon target in a gas mixture of argon and methane. The carbon content x was varied by varying the partial pressure of methane with respect to the total gas pressure. The dependence of the optical, structural and electrical properties on x has been investigated. With increasing x, the optical band gap increases owing to the hydrogenation of silicon in the region of small x and to the increase in the number of Si-C bonds in the large-x range, according to evidence from infrared spectra. While the dark conductivity decreases with increasing x, the photoconductivity shows a maximum at about x = 0·2. The photoconductivity increases in the range of x below 0·2 owing to the hydrogenation of silicon. Although it decreases in the range of x above 0·2, the values are larger than those of films prepared by glow-discharge decomposition of methane-silane gas mixtures reported in the literature. This is interpreted as being due to relatively simple bonding structures between carbon and hydrogen, owing to the deposition conditions of high power and low pressure, compared to the glow-discharge method.

Amorphous SiC: H thin films were prepared by the rf magnetron sputtering method using a composite target of silicon and graphite. The dependence of the optical, structural, electrical, and optoelectronic properties on the carbon content x was investigated, by measuring the optical absorption spectra, ir spectra, dark conductivity, photoconductivity and ESCA spectra. The optical gap was found to be unchanged with increasing x below about 0.6, in spite of the increase in the amount of the SiC bond. This is considered to be due to the formation of the carbon clusters. It is found that the photosensitivity shows a maximum at about x = 0.2, and is about one order of magnitude larger than the film with x = 0. This is related to the decrease in the dark conductivity, which is ascribed both to the formation of the SiC bond and to the reorganization of the defect-rich structure of sputter-deposited amorphous Si by the addition of about 20% carbon. The photoconductive effect was gradually lost in the range of x above 0.6. In this range, the optical gap increases rapidly owing to the rapid increase of the SiC bond. [ABSTRACT FROM AUTHOR]