Regular Article

Sensitivity of germanium content on growth conditions of silicon-germanium nanoparticles prepared in nonthermal capacitively-coupled plasmas^★

¹ Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
² Utrecht University, Debye Institute, P.O. Box 80000, 3508 TA Utrecht, The Netherlands

^* e-mail: jkr@iitm.ac.in

Received: 1 October 2019
Received in final form: 4 March 2020
Accepted: 16 April 2020
Published online: 6 August 2020

Abstract

We report on the synthesis of Si_1−x Ge _x alloy nanocrystals by very-high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) technique at different silane to germane gas flow ratio (R) in a mixture of (H₂+Ar) dilution gas and H₂ dilution gas alone. TEM, SAED, EDS studies and HAADF-STEM mapping of the samples were done to investigate the NCs' size, crystallinity and distribution of Si and Ge in the Si_1−x Ge _x alloy NCs. The average estimated size of the NCs in all the samples are in the order of exciton Bohr radius of Ge (24.3 nm), thereby indicating the probability of good quantum confinement. The alloy nature of NCs was confirmed in Raman study. The content of Ge in SiGe NCs was evaluated from Raman spectra which show a direct correlation with the fraction of hydrogen flow in the dilution gas mixture.