Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5005900 | Materials Science in Semiconductor Processing | 2017 | 5 Pages |
Abstract
The influence of crystallinity of as-deposited Ge films on Ge quantum dot (QD) formation via carbon (C)-mediated solid-phase epitaxy (SPE) was investigated. The samples were fabricated by solid-source molecular beam epitaxy (MBE). Ge/C/Si structure was formed by sequential deposition of C and Ge at deposition temperature (TD) of 150-400 °C, and it was heat-treated in the MBE chamber at 650 °C. In the case of amorphous or a mixture of amorphous and nano-crystalline Ge film grown for TD â¤250 °C, density of QDs increased with increasing TD due to the increase of C-Ge bonds in Ge layer. Ge QDs with diameter of 9.2±2.1 nm were formed in the highest density of 8.3Ã1011 cmâ2 for TD =250 °C. On the contrary, in the case of polycrystalline Ge film for TD â¥300 °C, density of QDs decreased slightly. This is because C incorporation into Ge layer during SPE was suppressed due to the as-crystallized columnar grains. These results suggest that as-deposited Ge film in a mixture of amorphous and nano-crystalline state is suitable to form small and dense Ge QDs via C-mediated SPE.
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Authors
Kaito Takeshima, Yuhki Itoh, Tomoyuki Kawashima, Katsuyoshi Washio,