Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 9: Focussed Session: Doped Si nanostructures (joint session with HL)

DS 9.4: Hauptvortrag

Dienstag, 17. März 2015, 10:45–11:15, H 2032

Active Silicon Nanovolume Doping: Failure and Alternatives — •Dirk König — University of New South Wales, Sydney, Australia

We report on phosphorous (P) doping of SiNC/SiO2 systems [1]. Relevant P configurations within SiNCs, at SiNC surfaces, within the sub-oxide interface shell and in the SiO2 matrix were evaluated by hybrid (h-) DFT. Atom probe tomography (APT) and its statistical evaluation provide detailed spatial P distributions. We obtain ionisation states of P atoms in SiNC/SiO2 systems at room temperature using X-ray absorption near edge structure (XANES) spectroscopy. P K shell energies were confirmed by h-DFT. While P diffuses into SiNCs and predominantly resides on interstitial sites, its ionization probability is extremely low; free localized electrons to SiNCs are not provided.

As alternative, SiO2 and Si3N4 create substantial energy offsets of electronic states in SiNCs [2]. h-DFT, interface charge transfer and experimental verifications arrive at the same NC size below which the embedding dielectric dominates their electronic properties. An increased energy gap was found for Si NCs in Si3N4 vs. SiO2 by h-DFT and confirmed in experiment. We describe the interface impact as nanoscopic field effect and show that the energy offset is very robust and controllable. As application example, we propose an undoped CMOS-able and CMOS technology-compatible Si-Nanowire MISFET.

[1] D. König, S. Gutsch, H. Gnaser et al., Nature Sci. Rep., accepted for publication (2014)

[2] D. König, D. Hiller, S. Gutsch et al., Adv. Mater. Interf. (2014); http://onlinelibrary.wiley.com/doi/10.1002/admi.201400359/abstract