Self-ion implantation and structural relaxation in amorphous silicon

Author(s): J. M. Gibson, Rob Elliman, T. Susi, C. Mangler
Abstract: Self-ion implantation amorphization is an established approach to study the structure and properties of amorphous silicon (a-Si). Fluctuation electron microscopy has consistently observed Medium-Range Order (MRO) in this system that is not consistent with the Continuous Random Network (CRN) model. Using this technique, we find that the degree of MRO first increases on thermal annealing and then decreases before finally recrystallizing. We discuss this new result in the light of previous experimental studies and recent theoretical observations on the favorability of the paracrystalline (PC) model over the CRN in a-Si. At ion doses far above the minimum required to amorphize, a high defect density is found in the PC phase, which anneals out at 500 °C. The PC structure after 500 °C annealing is independent of the initial implantation conditions and appears to represent a metastable and highly ordered structure. Higher-temperature annealing causes a reduction in the degree of MRO and the structure approaches but does not reach a fully CRN before eventually crystallizing above 600 °C. The effect of high-dose implantation is to increase the defect density in the as-implanted state, and the annealing of these defects is likely responsible for the large characteristic heat evolution at low temperature.
Organisation(s): Physics of Nanostructured Materials
External organisation(s): FAMU-FSU College of Engineering, Australian National University
Journal: Journal of Applied Physics
Volume: 138
No. of pages: 9
ISSN: 0021-8979
DOI: https://doi.org/10.48550/arXiv.2506.00176
Publication date: 07-2025
Peer reviewed: Yes
Austrian Fields of Science 2012: 103018 Materials physics, 103029 Statistical physics
ASJC Scopus subject areas: General Physics and Astronomy
Portal url: https://ucrisportal.univie.ac.at/en/publications/9934f97b-8d60-4e70-92dd-3ef17f9f1d62