The influence of pressure on growth of 3C-SiC heteroepitaxial layers on silicon substrates
|Dominika N. Teklińska 1,2, Iwona Jóźwik-Biała 1, Kacper Grodecki 1,3, Piotr Caban 1, A. Olszyna 2, Wlodek Strupinski 1|
1. Institute of Electronic Materials Technology (ITME), Wólczyńska 133, Warszawa 01-919, Poland
Epitaxial growth of cubic silicon carbide on silicon is a promising alternative, which provides low-cost substrates for growth of other wide band gap materials (GaN, graphene, etc.) for electronic applications. The main factors preventing a large scale development of 3C-SiC/Si technology are the lattice mismatch (~20%) and the difference in thermal expansion coefficients (~23% at a deposition temperature) between 3C-SiC layers and a Si substrate.
The top method to improve the crystalline quality of 3C-SiC is to grow a buffer layer prior to crystal growth because it helps to accommodate mismatches between SiC and Si. We observed that a carbonization layer was formed while silicon atoms, which out-diffused from the substrate, reacted with carbon atoms (precursor – propane). The thin 3C-SiC layer obtained in the carbonization process strongly affected the crystalline quality of subsequent 3C-SiC epilayers.
This mechanism led to generation of voids, which are a common interfacial defect associated with heteroepitaxial growth of 3C-SiC on Si. These defects were formed due to silicon out-diffusion, which resulted in coalescence of Si vacancies. The voids were formed at a different depth of the substrate. Moreover, the most common surface defects connected with growth of 3C-SiC on silicon were carbon inclusions.
The used samples were grown in a resistively heated horizontal hot-wall Chemical Vapor Deposition reactor. Epitaxial layers were grown on on-axis silicon substrates. The predominant goal was to analyze the relationship between the pressure used during growth and the crystalline quality of the obtained layers. Special attention was paid to homogeneity of the 3C-SiC layers obtained on silicon substrates. The morphology of the 3C-SiC buffer layer was investigated by scanning electron, atomic force and optical microscopies as well as Raman Spectroscopy.
Based on the results gathered in this work, it can be concluded that 20 mbar is the optimum process pressure. While using such growth conditions for 3C-SiC on silicon substrates, we can obtain a homogeneous layer without any carbon inclusions. Moreover, process pressure has influence on the crystalline quality of obtained 3C-SiC, which can be analyzed using AFM. The lowest roughness was obtained when using the appropriate value of pressure during growth. This proves that the 3C-SiC carbonization layer has much less stress in the interface between 3C-SiC and Si, which means the structure of the carbonization layer will have a better match to the substrate.
Acknowledgments: This work was supported by the SICMAT Project co-financed by the European Regional Development Fund under the Operational Programme Innovative Economy (Contract No. UDA-POIG.01.03.01-14-155/09).
Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 9, by Dominika N. Teklińska
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17
Submitted: 2013-05-27 10:13 Revised: 2013-05-27 10:13