We have investigated the effect of deoxyribonucleic acid (DNA) adsorption on a graphene field-effect-transistor (FET) device. We have used graphene which is grown on a Ni substrate by chemical vapour deposition. The Raman spectra of our graphene indicate its high quality, and also show that it consists of only a few layers. The current-voltage characteristics of our bare graphene strip FET show a hole conduction behavior, and the gate sensitivity of 0.0034 µA/V, which is reasonable with the size of the strip (510 µm2). After the adsorption of 30 base pairs single-stranded poly (dT) DNA molecules, the conductance and gate operation of the graphene FET exhibit almost 11% and 18% decrease from those of the bare graphene FET device. The observed change may suggest a large sensitivity for a small enough (nm size) graphene strip with larger semiconducting property.

We report successful bottom-up synthesis of small diameter silicon nanowires (SiNWs) on SiO2 and Si3N4 surfaces. SiNWs with diameter comparable to the diameter of the Au nano-particles (10-20 nm) were grown on these surfaces, as well as on Si substrates which are commonly used for the nanowire growth. The growth temperature for obtaining a high density of SiNWs on SiO2 and Si3N4 substrates is higher (460-470) than that of the case of normal Si substrates (440). The growth on patterned substrates demonstrates that SiNWs can be selectively grown. Furthermore, the guided growth over metal structures is also shown to be possible. Selective growth of SiNWs on pre-patterned surfaces opens up the possibility of self-aligning SiNWs for the integration of complex device structures.