| AVS 60th International Symposium and Exhibition | |
| Electronic Materials and Processing | Monday Sessions |
| Session EM-MoA |
| Session: | High-k Gate Oxides for High Mobility Semiconductors II |
| Presenter: | A. Molle, CNR-IMM, Italy |
| Authors: | A. Molle, CNR-IMM, Italy D. Chiappe, CNR-IMM, Italy E. Cinquanta, CNR-IMM, Italy C. Grazianetti, Università degli Studi di Milano Bicocca, Italy M. Fanciulli, Università degli Studi di Milano Bicocca, Italy |
| Correspondent: | Click to Email |
The silicon counterpart of graphene, the so called “silicene” [1,2], has been so far a theoretical option but its synthesis constituted a formidable challenge. Nonetheless, recent efforts have moved up this fascinating hypothesis to a concrete evidence [3][4] thus triggering a tremendous interest in silicene for electronic applications and fundamental investigations.
Non-trivial atomic arrangements of the silicene are expected to occur which are dictated by a delicate balance between planar and buckled bonding . Indeed, due to the large ionic radius of silicon, silicene is naturally prone to occur with a variety slightly-buckled configurations which can be driven by the silicene/substrate local interactions [1]. This structural complexity discriminates the experimentally observed silicene from graphene, and it is expected to bring basically new physical properties such as topological phase transitions, quantum spin Hall effect, or band gap opening [5]. Here we report on recent experimental results showing the formation of 2D epitaxial silicene on Ag(111) substrates [4] based on in situ scanning tunnelling microscopy-spectroscopy investigations.
Despite its structural flexibility, silicene is technologically limited by its chemical instability. Indeed, silicene undergoes oxidation when exposed to dry air. Then, interfacing silicene with a gate dielectric is essential for any feasible voltage bias application but also to barely save it from possibly destructive reactivity in ambient conditions.
While disentangling silicene from metallic templates is still an open challenge, on-top interface engineering of silicene is here addressed with the goal to develop a non-reactive encapsulation process. This effort enabled us to fabricate a chemically stable Al2O3/silicene/Ag heterostructure through a carefully tailored co-deposition of Al and O2 [6]. Raman spectroscopy was then used to demonstrate the structural stability of the encapsulated silicene. Finally, new hints at Si nanosheets grown on ad hoc 2D material templates are also discussed aiming at the silicene “portability” for device-oriented exploitation.
These outcomes disclose exceptionally novel issues in the physics of the emerging silicene and promote a renewed interest in nanoscaled silicon as active material for electronic devices.
References
1. S. Cahangirov, et al, Phys. Rev. Lett. 102, 236804 (2009).
2. M. Houssa, et al., Appl. Phys. Lett., 97, 112106 (2010).
3. P. Vogt, et al., Phys. Rev. Lett. 108, 155501 (2012).
4. D. Chiappe, et al., Adv. Mater. 24, 37, 5088 (2012).
5. M. Ezawa, Phys. Rev. Lett. 109, 055502 (2012).
6. A. Molle, et al., Adv. Func. Mat. 2013, 10.1002/adfm.201300354 (just accepted).