Abstract
Effects of intermediate carbon between amorphous Ge and Si surface on formation of Ge dots recrystallized through post-annealing were studied. The samples were prepared by solid-source molecular beam epitaxy system with electron beam gun for C sublimation and K-cell for Ge evaporation. C and Ge were deposited sequentially at 200 °C and Ge/C/Si was subsequently annealed in MBE chamber. Ge dots were formed at annealing temperature (TA) of 400 °C for Ge(1 nm)/C(0.25 ML)/Si. The dot size increased with TA, and both Ge(2 2 0) peak intensity measured by in-plane XRD and dot density were the highest at TA of 700 °C. A strong correlation between dot density and surface roughness indicated recrystallization of Ge occurred during the dot formation promoted by Si-C bonds. Concerning the effect of C coverage, there was an optimum at 0.25 ML which gave good crystallinity of Ge dots. Coalesced dots with bad crystallinity were observed for less or more C coverage. This was considered that dot formation combined with S-K growth mode due to large bare Si surface occurred at small C coverage and excess C incorporated into Ge dots at large C coverage. In terms of Ge thickness, there was also an optimum at 1 nm to provide sufficient Ge atoms without excess.
Original language | English |
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Pages (from-to) | 28-32 |
Number of pages | 5 |
Journal | Microelectronic Engineering |
Volume | 125 |
DOIs | |
Publication status | Published - 2014 Aug 1 |
Keywords
- Carbon
- Ge
- Molecular beam epitaxy (MBE)
- Quantum dot
- Si
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering