Matrix density effect on morphology of germanium nanocrystals embedded in silicon dioxide thin films

Date
2011
Authors
Alagoz, A. S.
Genisel, M. F.
Foss, Steinar
Finstad, T. G.
Turan, R.
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
Materials Research Society Symposium Proceedings
Print ISSN
0272-9172
Electronic ISSN
Publisher
Materials Research Society
Volume
1337
Issue
Pages
21 - 25
Language
English
Type
Article
Journal Title
Journal ISSN
Volume Title
Series
Abstract

Flash type electronic memories are the preferred format in code storage at complex programs running on fast processors and larger media files in portable electronics due to fast write/read operations, long rewrite life, high density and low cost of fabrication. Scaling limitations of top-down fabrication approaches can be overcome in next generation flash memories by replacing continuous floating gate with array of nanocrystals. Germanium (Ge) is a good candidate for nanocrystal based flash memories due its small band gap. In this work, we present effect of silicon dioxide (SiO 2) host matrix density on Ge nanocrystals morphology. Low density Ge+SiO 2 layers are deposited between high density SiO 2 layers by using off-angle magnetron sputter deposition. After high temperature post-annealing, faceted and elongated Ge nanocrystals formation is observed in low density layers. Effects of Ge concentration and annealing temperature on nanocrystal morphology and mean size were investigated by using transmission electron microscopy. Positive correlation between stress development and nanocrystal size is observed at Raman spectroscopy measurements. We concluded that non-uniform stress distribution on nanocrystals during growth is responsible from faceted and elongated nanocrystal morphology.

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Keywords
After high temperature, Annealing temperatures, Code storage, Complex programs, Electronic memories, Floating gates, Ge concentrations, Ge nanocrystals, Germanium nanocrystals, High density, Host matrices, Low costs, Low density, Magnetron sputter deposition, Matrix density, Mean size, Media files, Nanocrystal sizes, Nonuniform stress distribution, Off-angle, Portable electronics, Positive correlations, Post annealing, Scaling limitation, Spectroscopy measurements, Stress development, Top-down fabrication, Architectural acoustics, Computer architecture, Films, Flash memory, Functional materials, Germanium, Magnetrons, Morphology, Nonvolatile storage, Raman spectroscopy, Semiconducting silicon compounds, Silica, Silicon oxides, Stress concentration, Transmission electron microscopy, Nanocrystals
Citation
Published Version (Please cite this version)