Full band calculations of the intrinsic lower limit of contact resistivity

Maassen, Jesse; Jeong, Changwook; Baraskar, Ashish; Rodwell, M.J.W.; Lundstrom, Mark

doi:10.1063/1.4798238

Cited by 37 publications

(26 citation statements)

References 14 publications

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“…The in-plane thermoelectric properties of single-and double-layer MoS 2 are calculated using the Landauer transport formalism, which is equivalent to solving the Boltzmann equation in the case of diffusive transport 26,[40][41][42][43] . Here, we will briefly describe our approach to calculate the Seebeck coefficient and electrical conductivity using the full band dispersions obtained from the first-principles density functional theory (DFT).…”

Section: A2 Landauer Formalismmentioning

confidence: 99%

Gate-tunable and thickness-dependent electronic and thermoelectric transport in few-layer MoS2

Kayyalha

Maassen

Lundstrom

et al. 2016

Journal of Applied Physics

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Over the past few years, there has been a growing interest in layered transition metal dichalcogenides (TMD) such as molybdenum disulfide (MoS 2 ). Most studies so far have focused on the electronic and optoelectronic properties of single-layer MoS 2 , whose band structure features a direct bandgap, in sharp contrast to the indirect bandgap of thicker MoS 2 . In this paper, we present a systematic study of the thickness-dependent electrical and thermoelectric properties of few-layer MoS 2 . We observe that the electrical conductivity ( ) increases as we reduce the thickness of MoS 2 and peaks at about two layers, with six-time larger conductivity than our thickest sample (23-layer MoS 2 ). Using a back-gate voltage, we modulate the Fermi energy ( # ) of the sample where an increase in the Seebeck coefficient ( ) is observed with decreasing gate voltage ( # ) towards the subthreshold (OFF state) of the device, reaching as large as 500 µV/K in a four-layer MoS 2 .While previous reports have focused on a single-layer MoS 2 and measured Seebeck coefficient in the OFF state, which has vanishing electrical conductivity and thermoelectric power factor ( = / ), we show that MoS 2 -based devices in their ON state can have as large as > 50 12 345 6 in the two-layer sample. The increases with decreasing thickness then drops abruptly from double-layer to single-layer MoS 2 , a feature we suggest as due to a change in the energy dependence of the electron mean-free-path according to our theoretical calculation. Moreover, we show that care must be taken in thermoelectric measurements in the OFF state to avoid obtaining erroneously large Seebeck coefficients when the channel resistance is very high. Our study paves the way towards a more comprehensive examination of the thermoelectric performance of two-dimensional (2D)semiconductors.3

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Section: A2 Landauer Formalismmentioning

confidence: 99%

Gate-tunable and thickness-dependent electronic and thermoelectric transport in few-layer MoS2

Kayyalha

Maassen

Lundstrom

et al. 2016

Journal of Applied Physics

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“…From an atomistic modeling standpoint, Maassen et al 4 recently reported the lower limits of contact resistivity in Si using full band Tight Binding (TB) calculations. They report specific contact resistivities in the low 10 −11 Ω-cm 2 range at doping concentrations close to the solubility limit of P in Si (N d ≈ 7×10 20 cm −3 ) 5 .…”

mentioning

confidence: 99%

“…Figure 2 shows the transmission spectra that arise as a result of such a coupling for the two interface orientations considered in this work. Once the transverse momentum-resolved transmission spectra for the coupled interface are computed under the assumptions outlined above, the number of available conducting modes per unit cross sectional area as a function of energy E in Si, M (E), is simply calculated as per the mode-counting formalism outlined in Maassen et al 4 .…”

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confidence: 99%

Effect of realistic metal electronic structure on the lower limit of contact resistivity of epitaxial metal-semiconductor contacts

Hegde

Bowen

2014

Applied Physics Letters

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The effect of realistic metal electronic structure on the lower limit of resistivity in [100] oriented n-Si is investigated using full band Density Functional Theory and SemiEmpirical Tight Binding (TB) calculations. Using simulation unit cells guided by the interface chemistry of epitaxial CoSi 2 on [100] oriented Si observed experimentally, it is shown that the 'ideal metal' assumption fails in some situations and consequently underestimates the lower limit of contact resistivity in n-Si by at least an order of magnitude at high doping concentrations. The mismatch in transverse momentum space in the metal and the semiconductor, the so-called 'valley filtering effect', is shown to be dependent on the interface chemistry simulated. The results emphasize the need for explicit inclusion of the metal atomic and electronic structure in the atomistic modeling of transport across metal-semiconductor contacts.

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“…According to the ITRS roadmap [1], the maximum specific contact resistivity ρ c is required to be 1.5 × 10 −9 Ω.cm 2 by 2028 to meet the overall parasitic resistance requirement in the silicon (Si) MOSFET devices. In a theoretical study on the intrinsic limit of the contact resistivity within the ballistic trasport limit, it has been shown that the ITRS target is indeed possible from a theoretical perspective in a moderate doping density range for Si [2]. Yet, the lowest specific contact resistivity reported in an experiment so far for the p-type metal-semiconductor (M-S) contact (Pt-Si) is ρ c = 1.9×10 −9 Ω.cm 2 [3].…”

Section: Introductionmentioning

confidence: 99%

Specific contact resistivity of n-type Si and Ge M-S and M-I-S contacts

Kim

Oldiges

et al. 2015

2015 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD)

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We have theoretically investigated the specific contact resistivity of n-type Si and Ge metal-insulator-semiconductor contacts with various insulating oxides. We have found a significant reduction of the contact resistivity for both Si and Ge with an insertion of insulators at low and moderate donor doping levels. However, at the higher doping levels (>10 20 cm −3 ), the reduction of the contact resistivity is negligible and the contact resistivity increases as the insulator thickness increaes. Thus, we have shown that the lowest possible contact resistivity can be achieved with the metal-semiconductor contact with highest possible activated doping density.

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Full band calculations of the intrinsic lower limit of contact resistivity

Cited by 37 publications

References 14 publications

Gate-tunable and thickness-dependent electronic and thermoelectric transport in few-layer MoS2

Gate-tunable and thickness-dependent electronic and thermoelectric transport in few-layer MoS2

Effect of realistic metal electronic structure on the lower limit of contact resistivity of epitaxial metal-semiconductor contacts

Specific contact resistivity of n-type Si and Ge M-S and M-I-S contacts

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