Jilei Chen

Photovoltaic Effect and Evidence of Carrier Multiplication in Graphene Vertical Homojunctions with Asymmetrical Metal Contacts

Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metal-graphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.

Propagation characteristics of spin electromagnetic wave (SEW) in ferromagnetic film

In this paper, we investigate the propagation characteristics of spin electromagnetic wave (SEW) in ferromagnetic film. We calculate the amplitude and phase distribution of spin wave along propagating direction for MSSW mode and BVMSW mode. Two kinds of antenna probes are considered. And we simulate the amplitude and phase distribution of magnetic field around the antenna probe.