E. R. Viana, G. M. Ribeiro, J. C. Gonzalez, A. G. de Oliveira
A single tin oxide (SnO2) nanobelt was connected in a back-gate field-effect
transistor configuration. The device shows quantized conductance, in the form
of a current staircase enhancement in the drain current vs. gate voltage
characteristic curves. This current staircase, also called current
oscillations, is attributed to successive filling of energy subbands by
electrons, as a function of the applied gate voltage enhancement. Since the
quasi-Fermi energy level (Efermi) increases along with the gate voltage, the
channel conductance shows a step-change every time when Efermi coincides with
one subband edge. The origin of the subbands comes from the quantum confinement
of the carriers, in the plane perpendicular to the transport direction. The
oscillations could be identified and measured only for low values of
temperature, between 6K and 50K, and for low values of the drain voltage Vds,
between 1 and 100mV, in a nanobelt with cross section dimensions approximately
75nm x 175nm. We claim that the reported quantized conductance comes from the
field-induced confinement that created conditions for the emergence of the
"quantum wire" phenomena. In this way, at the present date our results show for
the first time in SnO2 nanobelts a fascinating quantum confinement effect in a
material that is expected to behave as bulk in the absence of gate field.
View original:
http://arxiv.org/abs/1201.3640
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