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A photodetector generating a nearly constant photocurrent in a very wide spectral range from ultraviolet (UV) to infrared has been demonstrated using chemical vapor deposited (CVD) graphene. Instability due to a photochemical reaction in the UV region has been minimized using an Al2O3 passivation layer, and a responsivity comparable to that of Highly Ordered Pyrolytic Graphite graphene photodetectors of 8mA/W has been achieved at a 0.1V bias, despite high defect density in the CVD graphene. A highly sensitive multi-band photodetector using graphene has many potential applications including optical interconnects, multi-band imaging sensors, highly sensitive motion detectors, etc. [ABSTRACT FROM AUTHOR]

Graphene field effect transistors (GFETs) with top-gate and back-gate structures have been extensively used without much consideration for compatibility with graphene. A comparative study of the electrical characteristics of buried-gate GFETs and top-gate GFETs revealed that the performance of buried-gate GFETs is drastically enhanced by having a better gate controllability, achieving three times higher field effect mobility (∼3000 cm2 V−1 s−1) than top-gate GFETs with on/off ratio ∼10. Carrier scattering was also substantially improved by minimizing the fringing field effect, which is found to be the origin of high series resistance in top-gate GFETs. Moreover, we showed by electromagnetic (EM) simulation that the electric field distribution inside the transistors is more uniform at the buried-gate GFETs than the top-gate GFETs. [ABSTRACT FROM AUTHOR]