Improvement of the Crystallinity of Silicon Films Deposited by Hot-Wire Chemical Vapor Deposition with Negative Substrate Bias

• Published in: Journal of electronic materials 2013-08, Vol.42 (8), p.2464-2469
• Main Authors: Zhang, Lei, Shen, Honglie, You, Jiayi
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemicals; Chemistry and Materials Science; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallization; Electronics and Microelectronics; Energy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Gases; Instrumentation; Materials Science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Optical and Electronic Materials; Photovoltaic conversion; Physics; Silicon; Solar cells. Photoelectrochemical cells; Solar energy; Solid State Physics; Solid-solid transitions; Specific phase transitions; Structure and morphology; thickness; Substrates; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-013-2608-x

We have investigated the effect of negative substrate bias on microcrystalline silicon films deposited on glass and stainless steel by hot-wire chemical vapor deposition (HWCVD) to gain insight into the effect of negative substrate bias on crystallization. Structural characterization of the silicon films was performed by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. It was found that the crystallinity of the films is obviously improved by applying the substrate bias, especially for films on stainless steel. At hot-wire temperature of 1800°C and negative substrate bias of −800 V, grain size as large as 200 nm was obtained on stainless-steel substrate with crystalline fraction 9% higher than that of films deposited on glass and 15% higher than that of films deposited without substrate bias. It is deduced that the improvement of the crystallinity is mainly related to the accelerated electrons emitted from the hot wires. The differences in this improvement between different substrates are caused by the different electrical potential of the substrates. A solar cell fabricated by HWCVD with −800 V substrate bias is demonstrated, showing an obviously higher conversion efficiency than that without substrate bias.