Silicon–hydrogen bond effects on aluminum-induced crystallization of hydrogenated amorphous silicon films

• Published in: Journal of crystal growth 2014-09, Vol.402, p.99-103
• Main Authors: Zhai, Xiaoli, Tan, Ruiqin, Wang, Weiyan, Huang, Jinhua, Zhuang, Fuqiang, Dai, Shixun, Song, Weijie
• Format: Article
• Language: English
• Subjects: A1. Crystallization; A3. Physical vapor deposition processes; Aluminum; Amorphous silicon; Applied sciences; B2. Semiconducting silicon; B3. Solar cells; Bonding; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallization; Deposition; Deposition by sputtering; Dilution; Energy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Hydrogen storage; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Photovoltaic conversion; Physics; Short range order; Solar cells. Photoelectrochemical cells; Solar energy; Solid-solid transitions; Specific phase transitions
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2014.05.013

The effects of hydrogen dilution on aluminum-induced crystallization (AIC) of hydrogenated amorphous silicon (a-Si:H) films have been studied. The Raman spectra showed that the short-range order (SRO) and the intermedium-range order (IRO) of the as-deposited a-Si films increased with the increase of the H2 dilution from 0% to 20%. The optical microscope (OM) and X-ray diffraction (XRD) observation revealed that, compared to the a-Si:H film deposited in pure Ar, the a-Si:H films deposited with H2 dilution in the range of 3–8% possessed a lower crystallization rate while the a-Si:H films deposited with high H2 dilution in the range of 15–20% possessed a faster crystallization rate. It was found that majority of the hydrogen existed in the form of monohydride (SiH) bond in the a-Si:H films with H2 dilution ratio of 3–8%, the bonding energy of which was higher than that of Si–Si bond, leading to a lower crystallization rate of a-Si:H films. While the dihydride (SiH2) bond became dominant in the a-Si:H films with high H2 dilution of 15–20%, the bonding energy of which was lower than that of Si–Si bond, thus accelerating the crystallization rate. Therefore, it was illustrated that not the hydrogen concentration but the form of silicon–hydrogen bond determined the AIC process of a-Si:H films. •Si–H2 bonds became dominant compared to Si–H bonds with the increase of H2 dilution.•Crystallization of a-Si:H films with 3–8% H2 dilution were lower than a-Si films.•Crystallization of a-Si:H films with 15–20% H2 dilution were faster than a-Si films.•The form of Si–H bond determined the AIC process of a-Si:H films.