The giant piezoresistance effect (PRE) of semiconductors as featured by a high gauge factor (GF) is recognized as the prerequisite for realizing optimal pressure sensors with desired high sensitivity. In this work, we report the discovery of giant PRE in SiC nanobelts with a record GF measured using an atomic force microscope. The transverse piezoresistance coefficient along the [111] direction reaches as high as −312.51 × 10–11 pa–1 with a corresponding GF up to −1875.1, which is twice more than the highest value ever reported on SiC nanomaterials. The first-principles calculations reveal that B doping turns the acceptor states in the bandgap into deeper impurity levels, which makes the major contribution to the observed giant piezoresistance behavior. Our result provides new insights on designing pressure sensors based on SiC nanomaterials.
In the present work, high-performance photodetectors (PDs) based on a single B-doped 3 C -SiC nanobelt, which are synthesized via catalyst-free pyrolysis of polymeric precursors of polysilazane, are reported. The as-built PDs have a high responsivity and external quantum efficiency of 6.37 × 10 5 A · W −1 and 2.0 × 10 8 % under 405 nm light with a power density of 0.14 mW · cm −2 at 5 V, respectively. The detectivity of the PDs is measured to be of 6.86 × 10 14 Jones. Moreover, the B-doped 3 C -SiC nanobelt PDs exhibit a long-term stability against 300 °C up to 180 days, suggesting their promising applications to be served under harsh conditions.
To ensure the performance of C/C composites, a surface-modified C/C composite was prepared with a C/C composite as the substrate, one-dimensional SiC as the intermediate, and vertically oriented graphene as the modification material without changing the microstructure or composition of the C/C composites. C/C composite surface modifications were prepared in two steps. Its specific surface area is improved from 0.25 m 2 /g to 10.44 m 2 /g, and the electromagnetic interference shielding efficiency is enhanced from 13.08 dB to 23.86 dB. Different from the C/C composites without surface modification, the electromagnetic interference shielding mechanism of surface-modified C/C composites changed from electromagnetic reflection to the interaction of electromagnetic absorption and reflection. The reason is that the increased specific surface area elongates the transmission paths of the electromagnetic waves by multiple reflections, leading to significantly improved electromagnetic interference shielding efficiency.
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