Characterization and Properties of Ge_1–x–C_x:H Compounds Obtained by X‐ray CVD of Germane/Ethyne Systems: Effect of the Irradiation Dose

Abstract

Amorphous germanium carbides have been prepared by X-ray activated CVD from germane/ethyne systems containing from 10 % to 80 % of ethyne. The effects of the dosage on the composition, characteristics, and properties of the solids obtained have been investigated. The composition of the material is found to change depending on both the ethyne percentage in the mixture and the irradiation time. Electron paramagnetic resonance (EPR), X-ray diffraction (XRD) analysis, and infrared spectroscopy (IRS) results indicate that the solids are formed by a randomly bound network of carbon and germanium atoms with hydrogen atoms terminating all the dangling bonds. Optical gap values higher than 3.0 eV, and increasing with the carbon molar fraction of the solid, have been found.

Amorphous nonstoichiometric Ge1−x–Cx:H compounds obtained by radiolysis-chemical vapor deposition of germane/ethyne or germane/allene systems: A bonding and microstructure investigation performed by x-ray photoelectron spectroscopy and Raman spectroscopy

“…C -H n vibrations are observed in the 2800-3000 cm −1 range, 38,47 while the broadband between 1900 and 2150 cm −1 is attributable to Ge-H n bond vibrations. 38,40,48 In both cases, the signals are an envelope of partially overlapped bands. In the 2825-3000 cm −1 range the Raman spectra deconvolution ͓Fig.…”

“…38,40,48 The deconvolution has been attempted and results ͓Fig. 3͑b͔͒ indicate that six peaks contribute to the total intensity of this FIG.…”

“…38,40 Several bands are present in the spectra, due to the high hydrogen content making possible many different hydrogen terminating configurations, both on germanium and carbon atoms. In fact, the Raman spectra indicate that the hydrogen atoms are bonded both to carbon and germanium atoms.…”

“…Nonmonochromatized Mg K␣ ͑h = 1253.6 eV͒ x radiations were used to record core level spectra ͑C1s, Ge3d, and O1s͒ and the GeL 3 M 45 M 45 Auger signal; the spectra were energy referenced to the aliphatic-aromatic C-C species in the sample having a binding energy BE= 285.0 eV. 40 The analyzer resolving power is as high as ϳ3500 and spectral resolution, as experimentally measured at the Ag3d 5/2 core level, is ⌬E = 0.8 eV. Atomic ratios were calculated from peak intensities by using Scofield's cross section values after experimental confirmation on standards.…”

“…[32][33][34][35][36][37][38][39][40] Changing the hydrocarbon, its percentage in the irradiated mixture, or the irradiation time we have obtained materials in a wide range of composition and having characteristics and properties attractive for different applications. [32][33][34][35][36][37][38][39][40] One of the aspect concerning the study of these alloys which receives more scientific attention is the investigation on the morphological and structural characteristics, because they are related to the materials properties. Therefore, in this paper we present a bonding and microstructure study on Ge x C 1−x : H alloys obtained by radiolysis-CVD of GeH 4 and C 2 H 2 or C 3 H 4 ͑allene͒ mixtures performed by x-ray photoelectron spectroscopy.…”