High-frequency, 6.2ÅpN heterojunction diodes

Champlain, James G.; Magno, R.; Park, Doewon; Newman, H. S.; Boos, J.B.

doi:10.1016/j.sse.2011.07.010

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…It turns out that a low drain bias is helpful to get the highest maximum . This scaled gate series resistance shows much lower max at short channels and illustrates the importance of minimizing [20], which can be done in practice by adopting a T-gate architecture [50,51]. We find that max predicted by our model can go beyond 1 THz for channel lengths shorter than 50 nm.…”

Section: High Frequency Performancementioning

confidence: 66%

“…In figure 7 (a), , is represented for two (0.1 and 0.6 V). The dashed black lines represent , , which is the physical limit that no cutoff frequency could surpass for GFETs [20,31]. It comes out from the supposition that maximum group velocity achievable in graphene is the Fermi velocity , following the trend , ≈ (2 ) ⁄ .…”

Section: High Frequency Performancementioning

confidence: 99%

“…Since the fabrication of the first GFET [14], multiple analytical models have been developed to describe its transistor effect [15][16][17][18][19][20]. These models give insight into the physics of graphene but they do not take account of the 2D electrostatics.…”

Section: Introductionmentioning

confidence: 99%

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Short channel effects in graphene-based field effect transistors targeting radio-frequency applications

2016

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Channel length scaling in graphene field effect transistors (GFETs) is key in the pursuit of higher performance in radio frequency electronics for both rigid and flexible substrates. Although two-dimensional (2D) materials provide a superior immunity to Short Channel Effects (SCEs) than bulk materials, they could dominate in scaled GFETs. In this work, we have developed a model that calculates electron and hole transport along the graphene channel in a drift-diffusion basis, while considering the 2D electrostatics. Our model obtains the self-consistent solution of the 2D Poisson's equation coupled to the current continuity equation, the latter embedding an appropriate model for drift velocity saturation. We have studied the role played by the electrostatics and the velocity saturation in GFETs with short channel lengths . Severe scaling results in a high degradation of GFET output conductance. The extrinsic cutoff frequency follows a 1⁄ scaling trend, where the index fulfills ≤ 2. The case = 2 corresponds to long-channel GFETs with low source/drain series resistance, that is, devices where the channel resistance is controlling the drain current.For high series resistance, decreases down to = 1, and it degrades to values of < 1 because of the SCEs, especially at high drain bias. The model predicts high maximum oscillation frequencies above 1 THz for channel lengths below 100 nm, but, in order to obtain these frequencies, it is very important to minimize the gate series resistance. The model shows very good agreement with experimental current voltage curves obtained from short channel GFETs and also reproduces negative differential resistance, which is due to a reduction of diffusion current.The RF FoMs strongly depend on the particular values of and . A lower value of will result in a lowering of , while a higher value of will lower max . Short channels and/or high biases can make and strongly deviate from the long channel prediction, even if the 2D character of graphene provides a superior control over the charge in the channel when compared to bulk materials. This is due to the fact that SCEs degrade the ability of the gate to control electrostatically the carrier concentration in the channel. In

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Section: High Frequency Performancementioning

confidence: 66%

Section: High Frequency Performancementioning

confidence: 99%

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Short channel effects in graphene-based field effect transistors targeting radio-frequency applications

2016

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“…El sistema dispersor consiste de un pozo de potencial 2D (capa de GaAs) entre dos barreras de potencial 2D (capa de Al 0 7 Ga 0 3 As) sujetos, tanto las barreras como el pozo, a una fuerza eléctrica longitudinal y a una fuerza eléctrica transversal, ambas aplicadas de manera externa. Se espera que éste sistema dispersor presente tunelaje resonante y al mismo tiempo que la fuerza eléctrica transversal acople canales.En particular, los dispositivos a base de tunelaje resonante son de considerable interes, ya que una gran variedad de aplicaciones pueden ser realizadas con gran éxito[5,6].Por todo lo mencionando anteriormente, consideramos necesario el estudio teórico del fenómeno del tunelaje resonante en heteroestructuras semiconductoras.…”

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Transporte multicanal en heteroestructuras que están en presencia de campos eléctricos

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Growth and optimization of InxGayAl1−x−ySb buffer layers for electronic and optoelectronic applications

Magno

Glaser

Podpirka

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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InxGayAl1−x−ySb alloys have been grown by molecular beam epitaxy for use as a buffer layer for growing semiconductors on GaAs substrates with lattice constants beyond that of AlSb. This is an extension of the use of AlxGa1−xSb alloys to accommodate for the lattice mismatch with semi-insulating GaAs substrates. The growth of In0.21Ga0.19Al0.6Sb with a 6.2 Å lattice constant on semi-insulating GaAs substrates is the focus of this work. Several measures of the quality of a 1 μm-thick In0.21Ga0.19Al0.6Sb layer improved when the growth temperature was increased from 460 to 600 °C. Atomic force microscopy root-mean-square values decreased from 2.9 to 1.8 nm and the peak-to-valley values decreased from 17.7 to 9.7 nm. In addition, double crystal x-ray diffraction ω-2Θ spectra linewidths decreased from 568 to 482 arc sec. At the lower growth temperatures, several photoluminescence (PL) peaks associated with radiative recombination from regions with different alloy compositions were found. However, on increasing the growth temperature a single PL line was observed, strongly suggesting a more uniform alloy composition.

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High-frequency, 6.2ÅpN heterojunction diodes

Cited by 3 publications

References 17 publications

Short channel effects in graphene-based field effect transistors targeting radio-frequency applications

Short channel effects in graphene-based field effect transistors targeting radio-frequency applications

Transporte multicanal en heteroestructuras que están en presencia de campos eléctricos

Growth and optimization of InxGayAl1−x−ySb buffer layers for electronic and optoelectronic applications

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