Fast Track Article

Control of crystalline volume and nano crystal grain size in nanocrystalline silicon thin film deposited by PECVD

Laboratory for Nanotechnology (LNT), Vietnam National University – Ho Chi Minh City (VNU-HCM) 70000, Vietnam

^a e-mail: dmchien@yahoo.com

Received: 12 September 2014
Revised: 9 October 2014
Accepted: 13 October 2014
Published online: 18 November 2014

Abstract

Application of the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique was studied to fabricate amorphous and nanocrystalline silicon (a-Si and nc-Si) thin films for photovoltaic devices at substrate temperature of 200 °C. Amorphous-crystalline transition of silicon thin films in working conditions of PECVD system was shown as a function of deposition parameters, i.e., dilution ratio of silane (SiH₄) in hydrogen, total gas pressure during deposition and RF excitation power density. The crystalline volume as well as grain size of nanocrystalline silicon films could be successfully controlled by tuning those deposition parameters. Micro Raman scattering spectroscopy and spectroscopic ellipsometry (SE) methods were used to characterize the structure and crystallization of the deposited silicon thin films. We could make nc-Si thin films with various crystalline volumes. Nc-Si grain size was also controlled and was in the range of 3–5 nm.