Superior long term stability of SiC nanowires over Si nanowires under physiological conditions

Semiconducting nanowires (NWs) are raising a growing interest in nanoelectronic devices. While silicon is the most widely used material in this field, it lacks long-term stability in aqueous solution. The usage of Si must hence be reconsidered for specific applications such as devices operating in biological media with high ionic strength. Silicon carbide is a wide bandgap semiconductor that can efficiently replace Si for applications in harsh environments or high temperature thanks to its high chemical stability and thermal conductivity. Here, we compare the long term stability of Si and SiC NWs under mimicked physiological conditions. The degradation kinetics of both types of NWs was studied from accurate monitoring of their cross-sectional geometry by transmission electron microscopy (TEM) over a period of 4 weeks. Results show a linear dissolution of Si NWs whereas SiC NWs exhibit much slower degradation kinetics confirming the superior chemical stability of SiC nanostructures over Si. After 32 days, NWs with an initial diameter of 20 nm are expected to dissolve completely in the case of Si NWs while SiC NWs would shrink by only 16%. (paper)