Local heat dissipation and elasticity of suspended silicon nanowires revealed by dual scanning electron and thermal microscopies
Résumé
A novel combined setup, with a Scanning Thermal Microscope (SThM) embedded
in a Scanning Electron Microscope (SEM), is used to characterize a suspended silicon
rough nanowire, which is epitaxially clamped at both sides and therefore monolithically integrated in a microfabricated device. The rough nature of the nanowire surface,
which prohibits vacuum-SThM due to loose contact for heat dissipation, is circumvented by decorating the wire with periodic platinum dots. Reproducible approaches
over these dots, enabled by the live feedback image provided by the SEM, yield a strong
improvement in thermal contact resistance and a higher accuracy in its estimation. The
results – thermal resistance at the tip-sample contact of 188 ±3.7 K/µW and thermal
conductivity of the nanowire of 13.7 ±1.6W/m·K – are obtained by performing a series
of approach curves on the dots. Noteworthy, the technique allows measuring elastic
properties at the same time – the moment of inertia of the nanowire is found to be
(6.1 ±1.0) ×10−30 m4 –, which permits to correlate the respective effects of the rough
shell on heat dissipation and on the nanowire stiffness. The work highlights the capabilities of the dual SThM/SEM instrument, in particular the interest of systematic
approach curves with well-positioned and monitored tip motion.
Domaines
Autre [cond-mat.other]
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