Impact of deposition parameters on the material quality of SPC poly-Si thin films using high-rate PECVD of a-Si:H

¹ Solar Energy Research Institute of Singapore, National University of Singapore, 7 Engineering Drive 1, 117574 Singapore, Singapore
² Department of Electrical and Computer Engineering, National University of Singapore, 117583 Singapore, Singapore
³ Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, 117602 Singapore, Singapore

^a e-mail: avishek.kumar@nus.edu.sg

Received: 23 September 2014
Accepted: 4 May 2015
Published online: 27 May 2015

Abstract

The impact of the deposition parameters such as gas flow (sccm) and RF plasma power density (W/cm²) on the deposition rate of a-Si:H films is systematically investigated. A high deposition rate of up to 146 nm/min at 13.56 MHz is achieved for the a-Si:H films deposited with high lateral uniformity on 30 × 40 cm² large-area glass substrates. A relationship between the SiH₄ gas flow and the RF power density is established. The SiH₄ gas flow to RF power density ratio of about 2.4 sccm/mW cm^-2 is found to give a linear increase in the deposition rate. The influence of the deposition rate on the material quality is studied using UV-VIS-NIR spectrophotometer and Raman characterisation techniques. Poly-Si thin film with crystal quality as high as 90% of single-crystalline Si wafer is obtained from the SPC of high rate deposited a-Si:H films.