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Structural and Compositional Evolution of Self-Assembled Germanium Islands on Silicon (001) During High Growth Rate LPCVD

Structural and Compositional Evolution of Self-Assembled Germanium Islands on Silicon (001) During High Growth Rate LPCVD
Structural and Compositional Evolution of Self-Assembled Germanium Islands on Silicon (001) During High Growth Rate LPCVD
Understanding the process of self-organization of Ge nanostructures on Si with controlled size distribution is a key requirement for their application to devices. In this study, we investigate the temporal evolution of self-assembled islands during the low pressure chemical vapour deposition (LPCVD) of Ge on Si at 650 Degrees C using high growth rates (6-9nm/min). The islands were characterized by atomic force microscopy, transmission electron microscopy, Rutherford backscattering spectrometry and micro-Raman spectroscopy. We found that the first nanostructures to assemble were small islands, with a narrow size distribution, typical of the "lens-shaped" structures reported in previous studies. Next to form were a population of larger "lens-shaped" islands with a similar surface density to that of the small islands, but with broad height and width distributions. These islands differ from the pyramid-shaped islands previously reported for a similar size range. On further Ge deposition, the population evolves into one of the large square-based truncated pyramids with a very narrow size distribution. Such pyramidal structures were previously reported at smaller sizes. Furthermore, we see no evidence of the multifaceted domes previously reported in this size range. The small "lens-shaped" islands appear to be strained, whilst some of the intermediate-sized islands and all the large truncated pyramids contain misfit strain relaxation induced defects. Additionally, in the both the intermediate size "lens-shaped" islands and the large truncated pyramidal islands, there is evidence of Si-Ge strain-induced alloying, more significant in the first than in the latter. Our observation of "lens-shaped" islands and truncated pyramids at larger sizes than are normally observed, suggests a kinetically driven process that delays the evolution of energetically favourable island structures until larger island sizes are reached.
25.1-25.6
Dilliway, Gabriella D M
91df2709-ddc5-418f-9844-7dae80e37f5b
Cowern, Nicholas E B
9058967b-1363-43f8-8453-6856ca391499
Jeynes, Chris
8ea089ab-2b7b-4d09-a8b7-fe0efa22913e
O'Reilly, Lisa
dac79718-e4bf-4d8c-a410-b7743487c478
McNally, Patrick J
577b68f4-9a99-49a7-8fcb-4ecb8a3c4d24
Bagnall, Darren M
5d84abc8-77e5-43f7-97cb-e28533f25ef1
Dilliway, Gabriella D M
91df2709-ddc5-418f-9844-7dae80e37f5b
Cowern, Nicholas E B
9058967b-1363-43f8-8453-6856ca391499
Jeynes, Chris
8ea089ab-2b7b-4d09-a8b7-fe0efa22913e
O'Reilly, Lisa
dac79718-e4bf-4d8c-a410-b7743487c478
McNally, Patrick J
577b68f4-9a99-49a7-8fcb-4ecb8a3c4d24
Bagnall, Darren M
5d84abc8-77e5-43f7-97cb-e28533f25ef1

Dilliway, Gabriella D M, Cowern, Nicholas E B, Jeynes, Chris, O'Reilly, Lisa, McNally, Patrick J and Bagnall, Darren M (2003) Structural and Compositional Evolution of Self-Assembled Germanium Islands on Silicon (001) During High Growth Rate LPCVD. Mat Res Soc Symp Proc. 25.1-25.6 .

Record type: Conference or Workshop Item (Paper)

Abstract

Understanding the process of self-organization of Ge nanostructures on Si with controlled size distribution is a key requirement for their application to devices. In this study, we investigate the temporal evolution of self-assembled islands during the low pressure chemical vapour deposition (LPCVD) of Ge on Si at 650 Degrees C using high growth rates (6-9nm/min). The islands were characterized by atomic force microscopy, transmission electron microscopy, Rutherford backscattering spectrometry and micro-Raman spectroscopy. We found that the first nanostructures to assemble were small islands, with a narrow size distribution, typical of the "lens-shaped" structures reported in previous studies. Next to form were a population of larger "lens-shaped" islands with a similar surface density to that of the small islands, but with broad height and width distributions. These islands differ from the pyramid-shaped islands previously reported for a similar size range. On further Ge deposition, the population evolves into one of the large square-based truncated pyramids with a very narrow size distribution. Such pyramidal structures were previously reported at smaller sizes. Furthermore, we see no evidence of the multifaceted domes previously reported in this size range. The small "lens-shaped" islands appear to be strained, whilst some of the intermediate-sized islands and all the large truncated pyramids contain misfit strain relaxation induced defects. Additionally, in the both the intermediate size "lens-shaped" islands and the large truncated pyramidal islands, there is evidence of Si-Ge strain-induced alloying, more significant in the first than in the latter. Our observation of "lens-shaped" islands and truncated pyramids at larger sizes than are normally observed, suggests a kinetically driven process that delays the evolution of energetically favourable island structures until larger island sizes are reached.

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Published date: 2003
Additional Information: Event Dates: December 2003
Venue - Dates: Mat Res Soc Symp Proc, 2003-12-01
Organisations: Nanoelectronics and Nanotechnology

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Local EPrints ID: 258683
URI: https://eprints.soton.ac.uk/id/eprint/258683
PURE UUID: 9d9ea409-8d03-4bd9-8606-af0246b20f58

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Date deposited: 15 Dec 2003
Last modified: 19 Jul 2019 22:42

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