Electron accumulation in graphene by interaction with optically excited quantum dots

Zero-dimensional semiconductor nanocrystals (quantum dots) are known to interact with other metallic or semiconductor medium by means of resonant energy transfer or transfer of electronic charge. In the present work we demonstrate efficient electronic interaction of quantum dots and recently discovered graphene, single atom thick two-dimensional carbon crystal. Transfer of optically generated carriers from a quantum dot to graphene is seen by the quench of quantum dots photoluminescence and confirmed by the electrical measurements on single-layer graphene transistor. The phenomenon reported could find an application in graphene-based optical switching and light harvesting. © 2010 Elsevier B.V. All rights reserved.status: publishe

Metal to semiconductor transition in graphene by oxygen plasma treatment: a building block for graphene-based electronics

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Chemically enhanced double-gate bilayer graphene field-effect transistor with neutral channel for logic applications

In this article, we present the simulation, fabrication, and characterization of a novel bilayer graphene field-effect transistor exhibiting electron mobility up to ~1600 cm(2) V(-1) s(-1), a room temperature I on/I off ≈ 60, and the lowest total charge (~10(11) cm(-2)) reported to date. This is achieved by combined electrostatic and chemical doping of bilayer graphene, which enables one to switch off the device at zero top-gate voltage. Using density functional theory and atomistic simulations, we obtain physical insight into the impact of chemical and electrostatic doping on bandgap opening of bilayer graphene and the effect of metal contacts on the operation of the device. Our results represent a step forward in the use of bilayer graphene for high-performance logic devices in the beyond-complementary metal-oxide-semiconductor (CMOS) technology paradigm.status: publishe

Self-seeded, position-controlled InAs nanowire growth on Si: A growth parameter study

In this work, the nucleation and growth of InAs nanowires on patterned SiO2/Si(111) substrates is studied. It is found that the nanowire yield is strongly dependent on the size of the etched holes in the SiO2, where openings smaller than 180 nm lead to a substantial decrease in nucleation yield, while openings larger than ≈ 500 nm≈500nm promote nucleation of crystallites rather than nanowires. We propose that this is a result of indium particle formation prior to nanowire growth, where the size of the indium particles, under constant growth parameters, is strongly influenced by the size of the openings in the SiO2 film. Nanowires overgrowing the etched holes, eventually leading to a merging of neighboring nanowires, shed light into the growth mechanism