2016，High performance, visible to mid-infrared photodetector based on graphene nanoribbons passivated by HfO2
Abstract
Graphene has drawn tremendous attention as a promising candidate for electronic and optoelectronic applications owing to its extraordinary properties, such as broadband absorption and ultrahigh mobility. Nevertheless, the absence of bandgap makes graphene unfavorable for digital electronic or photonic applications. Although patterning graphene into nanostructures with quantum confinement effect is able to open a bandgap, devices based on these graphene nanostructures generally suffer from the low carrier mobility and scattering losses. In this paper, we demonstrated that encapsulation of atomic layer deposited high-quality HfO2 film will greatly enhance the carrier mobility and decrease the scattering losses of graphene nanoribbon, because this high-k dielectric layer weakens carrier Coulombic interactions. In addition, photodetector based on HfO2 layer capped graphene nanoribbons can cover a broadband wavelength from visible to mid-infrared at room temperature, exhibiting ~10 times higher responsivity than the one without HfO2 layer in visible regime and ~8 times higher in mid-infrared regime. The method employed here could be potentially used as a general approach to improve the performance of graphene nanostructures for electronic and optoelectronic applications.