Effect of Substrate Temperature on (Micro/Nano)Structure of a-SiC:H Thin Films Deposited by Radio-Frequency Magnetron Sputtering.

Abstract

The nature of the hydrogen bonds and their influence on film (micro/nano)structure has been investigated as a function of substrate temperature T S (200–500 °C) in hydrogenated amorphous silicon carbide (a-SiC:H) thin films. These films were prepared by radio-frequency magnetron sputtering at a common pressure and high hydrogen dilution in the gas phase mixture (Ar + 80% H2). Infrared absorption and Raman spectroscopy experiments have been carried out to characterize the (micro/nano)structure of different series as a function of T S. The results of Fourier transform infrared spectroscopy indicate that all series are characterized by the presence of the low Si–H n and C–H n bond concentration and no absorption band at 2000 cm–1 attributed to isolated monohydride Si–H can be detected, which suggests that the hydrogen is predominantly bonded as polyhydride groups (Si–H2) n , giving the band at 2090 cm–1. The concentration of the Si–C bond and the crystalline fraction, which increase with increasing T S, show an improvement in the crystallinity of the films. The influence of T S on the growth of crystalline nanograins is studied by Raman spectroscopy. At temperatures T S ≥ 200 °C, these films contain Si–C crystallites in addition to the Si nanocrystals distributed in the amorphous network. The Si crystallite size is unaffected by the increase of T S but the size of graphitic domains is reduced and their distribution becomes more disordered. Results of Raman spectroscopy show also that the high values obtained for the line width of transverse acoustic TA-like band toward low frequencies justifies the deconvolution of infrared spectra taking into account the doublet (845 and 910 cm–1). The results of this paper therefore shed light on the origin of amorphous and nanocrystalline structure in the a-SiC:H thin films, which has been a subject of debate for decades.

Spectroscopic and microscopic studies of self-assembled nc-Si/a-SiC thin films grown by low pressure high density spontaneous plasma processing

“…In the present investigation, during a systematic increase in R(CH 4 /SiH 4 ) in the plasma, C has been increasingly incorporated in the amorphous matrix (without forming the crystalline Si-C network 28 ) within which embedded Si-ncs change in volume fraction. Hence, the optical properties of the amorphous component change consistently along with the simultaneous changes in the overall structural composition of the network.…”

Raman identification of lonsdaleite in Popigai impactites

“…Finally, we should mention that asymmetric and symmetric contour approaches for deconvolution of Raman spectra of nanoparticles are extensively applied to characterize the Si,C‐based films . Reliability and unambiguity of the deconvolution results strongly depend on the deconvolution model and the quality of experimental spectra.…”

Incompatibility of Pure SnO2 Thin Films for Room-Temperature Gas Sensing Application

“…This might be due to insufficient thermal energy to complete the oxidation process of Sn at low temperatures. As the temperature is increased, Sn oxidizes completely and more crystalline films are achieved. − Furthermore, there is growth in the (200) direction as the substrate temperature increases. The schematic diagram representing the processes happening in the deposition of the thin film through spray pyrolysis under different temperature conditions (low to high) is given in Figure .…”