Effect of contact barrier on electron transport in graphene

Zhou, Yang-Bo; Han, Binghong; Liao, Zhi-Min; Zhao, Qing; Xu, Jun; Yu, Dapeng

doi:10.1063/1.3292029

Cited by 14 publications

(13 citation statements)

References 28 publications

(18 reference statements)

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“…11,28,29 It seems unlikely, however, that a similar mechanism would be of importance in our experiments, since the nonlinearity is weakly gate dependent. Other possibilities for nonlinearities include the presence of tunnel junctions 30 or contact phenomena, 31 but we can disregard them as an explanation of our measurements due to the weak length dependence of the nonlinear conductivity σ (V ). Furthermore, nonlinear current-voltage curves in graphene oxides have been explained with space-charge limited currents, 32 but such effects are likely to be negligible in metallic graphene, as also supported by the absence of any bias-doping effects in our simulations.…”

Section: Discussionmentioning

confidence: 99%

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Self-heating and nonlinear current-voltage characteristics in bilayer graphene

et al. 2011

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We demonstrate by experiments and numerical simulations that the low-temperature current-voltage characteristics in diffusive bilayer graphene (BLG) exhibit a strong superlinearity at finite bias voltages. The superlinearity is weakly dependent on doping and on the length of the graphene sample. This effect can be understood as a result of Joule heating. It is stronger in BLG than in monolayer graphene (MLG), since the conductivity of BLG is more sensitive to temperature due to the higher density of electronic states at the Dirac point.

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Section: Discussionmentioning

confidence: 99%

“…11,[28][29][30][31][32][33] In particular, Zener-Klein tunneling in MLG has been shown to give rise to superlinearities close to CNP. 11,28,29 It seems unlikely, however, that a similar mechanism would be of importance in our experiments, since the nonlinearity is weakly gate dependent.…”

Section: Discussionmentioning

confidence: 99%

Self-heating and nonlinear current-voltage characteristics in bilayer graphene

et al. 2011

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“…This nonlinearity in the currentvoltage curves can be explained by the infl uence of the barrier between graphene channel and metal-graphene interaction region at the electrodes. [27][28][29] (More details are in Supporting Information). Specially, when the voltage about 4.5 V, the current is seen to be saturated.…”

Section: Communicationmentioning

confidence: 99%

High Responsivity, Broadband, and Fast Graphene/Silicon Photodetector in Photoconductor Mode

Chen

Cheng

Wang

et al. 2015

Advanced Optical Materials

153

102

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COMMUNICATIONIn this paper, we present a highly broadband (from visible to infrared) photodetector based on chemical vapor deposition (CVD) graphene-silicon heterostructure, together to be operated in photoconductor mode. This device shows very high responsivity (>10 4 A W −1 ) at wavelength of 632 nm, where light absorption relies on silicon. More importantly, even in the infrared region (1550 nm), where light absorption only depends on the graphene, the responsivity of our detector can be as high as 0.23 A W −1 , which is much higher those by pure monolayer graphene-based devices without optically assisted structure in this spectral region. [ 13,15,24 ] The signifi cant response is mainly due to the fact that the built-in fi eld in heterostructure can effectively prolong the ultrashort lifetime of photon-induced carriers. Besides, we also fi nd three dynamic processes in the transient response: photo-induced carriers sweeping into graphene by the built-in fi eld, electrons in the depletion region diffusion back to graphene, and photo-induced carriers in the bulk silicon diffusion to graphene. Due to the fi rst mechanism, the response time of our detector is less than 3 µs, which has not been reported among graphene photoconductor/ phototransistors. [ 1 ] The structure of graphene-silicon heterostructural photodetector is schematically shown in Figure 1 a. The start wafer we employed is a lightly doped p-type silicon wafer (>100 Ω). A thin layer of SiO 2 is grown on silicon and patterned a window on top. Then, the CVD graphene (the Raman spectra is shown in Figure S1, Supporting Information) is transferred, and both electrodes are deposited on graphene. The SiO 2 layer can avoid the overlap between the electrode and silicon. A Schottky junction is thus formed at the interface between graphene and silicon. The Fermi level differences are measured by Kelvin probe force microscopy (KPFM) in the dark. As shown in Figure 1 b, the surface potential differences (approximately similar to the work function misalignment for clean samples) between graphene and silicon, and between graphene and gold are about 0.08 and 0.16 eV, respectively. Under ambient conditions, the work function of gold is around 4.8 to 4.9 eV. [ 25,26 ] By taking the intrinsic work function of graphene (≈4.56 eV) [30][31][32] into consideration, an energy band diagram is depicted in Figure 1 c. The Fermi energy of graphene should be around 0.16 to 0.26 eV. A built-in fi eld forms at the surface, which directs from silicon to graphene. The graphene not only functions as the charge transport channel, but also works as the light absorber for the light with photon energy lower than the Fermi energy.In the visible light experiment, the photodetector is characterized by the laser at wavelength of 625 nm. Optical attenuators are introduced to change the input power. DOI: 10.1002/adom.201500127Graphene is thought to be an ideal material for novel photodetectors due to its unique properties. [1][2][3] For example, its zero bandgap affords the benefi t of ultr...

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“…The graphene samples on a Si substrate covered a 300-nm SiO 2 layer were fabricated through a mechanical exfoliation method [1,14]. Electrical contacts of Ti/Au (10/50 nm) electrodes on the both ends of the graphene sheet were fabricated via the processes of electron beam lithography, metal deposition and lift-off.…”

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confidence: 99%