Tunable p-type doping of Si nanostructures for near infrared light photodetector application

In this study, we present a simple oxide assisted p-type doping of Si nanostructures by evaporating a mixed powder composed of SiB6 and SiO. It was found that Si nanoribbons (Si NRs) which can be obtained at high SiB6 content, will give way to Si nanowires (Si NWs) when the content of SiB6 in the mixed powder was reduced. According to our transport measurement of field effect transistors (FETs) assembled on individual Si nanostructures, the as-prepared Si nanostructures with different boron doping levels all exhibit typical p-type conduction characteristics. Additionally, the electrical conductivity of the Si nanostructures can be tuned over 7 orders of magnitude from 8.98 x 10(2) S cm(-1) for the highly doped sample to 3.36 x 10(-5) S cm(-1) for the lightly doped sample. We also assembled a nano-photodetector based on monolayer graphene and the as-prepared Si nanostructures, which exhibits ultra-sensitivity to 850 nm near infrared light (NIR) illumination with a nanosecond response speed (tau(rise)/tau(fall): 181/233 ns). The generality of the above results suggest that the Si nanostructures are promising building blocks for future electronic and optoelectronic device applications.