Anomalous Piezoresistive Changes of Core-Shell Structured SIC Nanowires

Piezoresistive effects of core-shell silicon carbide (SiC) nanowires (NWs) were experimentally evaluated using a FET-type device with single SiC nanowire as a channel, by electrical resistivity measurement with changing gate voltages. The I
_d
-V
_g
characteristics with no straining showed change in FET behaviors from n-channel type to p-channel type by changing insulating shell from SiO
_x
to Al
₂
O
₃
due to the fixed charge in the shells. An influence of initial surface potential determined with the fixed charge in the insulating shells and gate voltages on the resistance change ratio at a small strain of SiCNWs was experimentally evaluated. Gauge factors at 1 % small strain of SiCNW differed from -21 to 40 between SiO
_x
-shell and Al
₂
O
₃
-shell SiCNWs due to the polarity of the fixed charge in the shells, and increased from 40 to 100 on Al
₂
O
₃
-shell SiCNW with a negative voltage increment from 0 to -0.5 V.