Paper NS+EN-MoA4
Hot Electron Generation Enhanced by Carrier Multiplication Probed with a Graphene/TiO₂ Nanodiode

Monday, November 10, 2014, 3:00 pm, Room 304

Graphene has attracted intensive attention for viable applications such as energy conversion and optoelectronic devices. When photons hit the graphene, the photon energy can be transferred to hot carriers above the Fermi level from the valence band of the graphene before the photon energy is lost as heat. The efficiency of the conversion depends on the interaction of photons with electrons/holes in the system. In graphene without a bandgap, the process of energy relaxation consists of the Auger process (impact ionization), which leads to carrier multiplication. Here, we fabricated a graphene/TiO₂ nanodiode to investigate carrier multiplication by experimental detection and theoretical confirmation of hot electron amplification. Our findings indicate that carrier multiplication of the graphene based on the strong electron–electron interaction is highly efficient, compared with Au/TiO₂ at a given photon energy. Multiple generations of hot electrons can induce photocurrent, which suggests the possibility of feasible applications such as photovoltaics and photodetectors.