Resistance Noise in Electrically Biased Bilayer Graphene

We have studied 1/f noise power SI in suspended bilayer graphene devices. Around the Dirac point, we observe ultra low noise amplitude on the order of f*SI/Ib2=10−9. The low frequency noise level is barely sensitive to intrinsic carrier density, but temperature and external doping are found to influence the noise power. In our current-annealed samples, the 1/f noise is dominated by resistance fluctuations at the contacts. Temperature dependence of the 1/f noise suggests the presence of trap states in the contact regions, with a nearly exponential distribution function displaying a characteristic energy of 0.12 eV. At 80 K, the noise displays an air pressure sensitivity that corresponds to ∼0.3 ppm gas detection sensitivity; this indicates the potential of suspended graphene as a platform for gas sensing applications.

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confidence: 97%

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confidence: 99%

Ultra low 1/f noise in suspended bilayer graphene

Kumar

Laitinen

Cox

et al. 2015

“…The noise level in graphene FETs is strongly affected by the quality of the graphene-metal contacts and environmental exposure [15]. Several reports suggested that the low-frequency noise can be reduced in bilayer graphene (BLG) devices as compared to that in the single-layer graphene (SLG) devices [11,14]. The physical mechanism for the reduction and the dominant noise sources, e.g.…”

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confidence: 99%

“…The low-frequency noise in graphene field-effect transistors (FETs) has the drain-current noise spectral density S I~1 /f for the frequency f below 100 kHz [11][12][13][14][15][16][17][18]. Some graphene devices also exhibit the generation-recombination (G-R) noise bulges with the time constants =1/(2f o ) of ~0.3 -1.1 s (f o is the corner frequency) [12].…”

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confidence: 99%

Graphene thickness-graded transistors with reduced electronic noise

Liu

Rumyantsev

Shur

et al. 2012

We demonstrate graphene thickness-graded transistors with high electron mobility and low 1/f noise (f is a frequency). The device channel is implemented with few-layer graphene with the thickness varied from a single layer in the middle to few-layers at the source and drain contacts. It was found that such devices have electron mobility comparable to the reference single-layer graphene devices while producing lower noise levels. The metal doping of graphene and difference in the electron density of states between the single-layer and few-layer graphene cause the observed noise reduction. The results shed light on the noise origin in graphene.

“…Flicker noise in graphene arises from the fluctuation in the number of charge carriers and their mobility. Techniques to reduce it such as electron irradiation [28][29][30][31][32] can be explored in this context. In addition, the high NEP in graphene is also due to the low sensitivity arising in part because of the weak dependence of the graphene resistance with temperature.…”

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confidence: 99%

Limits on the bolometric response of graphene due to flicker noise

Grover

Dubey

Mathew

et al. 2015

We study the photoresponse of graphene field effect transistors using scanning photocurrent microscopy in near and far field configurations, and we find that the response of graphene under a source-drain bias voltage away from the contacts is dominated by the bolometric effect caused by laser induced heating. We find no significant change in the photocurrent with the optical modulation frequency upto 100 kHz. Although the magnitude of the bolometric current scales with bias voltage, it also results in noise. The frequency dependence of this noise indicates that it has a 1/f character, scales with the bias voltage and limits the detectable bolometric photoresponse at low optical powers.Graphene 1 -an isolated single layer of graphitepromises to be useful for photodetection and other light harvesting devices because of its gapless band structure and large broadband absorption. Photodetectors made using graphene 2 involving global illumination have been reported and the quantities of interest are the responsivity and response time. In these measurements, the role of different mechanisms involved in photogeneration is complex. In a recent study, 3 the infrared photoresponse has been observed to change with the graphene channel length suggesting different physical mechanisms playing a role at the electrodes and far away from them.Scanning photocurrent microscopy (SPCM) measurements are useful in elucidating the mechanism of photocurrent generation in graphene since the spatially resolved mapping of current can yield information about the photoresponse at different regions on the graphene device such as contacts and p-n junctions. Several mechanisms 4 have been identified such as the photovoltaic, 5-8 photothermoelectric 9,10 and bolometric effects. 11In this paper, we discuss SPCM measurements on graphene field effect transistor (FET) devices using both near and far field configurations and focus on homogeneous graphene away from the electrodes. The photocurrent generation in graphene is dominated by the bolometric effect far away from the electrodes and by the photovoltaic effect due to the built-in electric field at the contacts. The bolometric effect refers to the resistance change induced in the device by laser-induced heating and it has previously been seen in carbon nanotubes, 12 graphene 11 and in 100 nm thick black phosphorus. 13 Our main finding is that the bolometric effect, which is only visible at non-zero bias voltages is accompanied by flicker noise which scales with bias and limits the detectable bolometric signal.Graphene devices were fabricated by exfoliation of graphite on degenerately doped silicon substrates with 300 nm of silicon dioxide. Monolayer graphene flakes were identified by visual contrast in optical microscope and with Raman spectroscopy. Electron beam lithograa) Electronic mail: deshmukh@tifr.res. in FIG. 1. Schematic of the (a) near-field and (b) far-field measurement setup. In (a), a tapered fiber is used for illumination (635 nm laser diode) as part of a home-built NSOM, and in (b...