Subband structure engineering for performance enhancement of Si MOSFETs

Takagi, Shinichi; Koga, J.; Toriumi, Akira

doi:10.1109/iedm.1997.650345

Cited by 104 publications

(84 citation statements)

References 2 publications

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“…It has already been reported [4], [5] that the value of 7 is different between electrons and holes on (100) surface. Also, the companion paper [8 J demonstrated in case of ( 100) surface that the E,R dependence of the electron mobility is different from that of the hole mobility.…”

Section: T Quite Useful For Characterizing the Inversion Layer Mobilimentioning

confidence: 97%

On the universality of inversion layer mobility in Si MOSFET's: Part I-effects of substrate impurity concentration

Takagi¹,

Toriumi

Iwase

et al. 1994

IEEE Trans. Electron Devices

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718

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Abstract-This paper reports the studies of the inversion layer mobilities in n-channel MOSFET's fabricated on Si wafers with three surface orientations ((loo), (110), and (111)) from the viewpoint of the universal relationship against the effective field, E,R(= q(A\-clpl + 11 . -Vh)/~Si). It is found that the universality does hold for the electron mobilities on (110) and ( l l l ) , when the value of 17 is taken to be 113, different ftom the electron mobility on (loo), where I ) is 1/2. Also, the E,ff dependence of the electron mobility is found to differ among (loo), (110), and (111) surfaces. This is attributed to the differences in the E v~ dependence of the mobility limited by surface roughness scattering among the orientations.The origins of E, m and '1 are discussed on the basis of the relaxation time approximation for a 2DEG (2-dimensional electron gas). While the surface orientation dependence of 11 in phonon scattering can be understood in terms of the subband occupation, it is found that the theoretical formulation of surface roughness scattering, used currently, needs to be refined in order to explain the differences in E,ff dependence and the value of 11 among the three orientations.

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Section: T Quite Useful For Characterizing the Inversion Layer Mobilimentioning

confidence: 97%

On the universality of inversion layer mobility in Si MOSFET's: Part I-effects of substrate impurity concentration

Takagi¹,

Toriumi

Iwase

et al. 1994

IEEE Trans. Electron Devices

Self Cite

1,398

718

View full text Add to dashboard Cite

show abstract

“…Early low-temperature studies revealed already that the parameter is not a constant with T [46], [50], [51], but lies somewhere between 1/3 and 1, which points towards a change in dominant scattering mechanism upon cooling. More recently, detailed studies have been reported on the substrate and doping density dependence of the low temperature peff [64]-1661, both for n-and for p-channel devices.…”

Section: Effective Mobility At Moderate Transverse Electric Fieldmentioning

confidence: 99%

“…In many cases, vsat is derived from the drift velocity vds of the carriers in the lateral electric field Es [73], which is given by the empirical model [61,[71,[731:…”

Section: Velocity Saturation and Overshootmentioning

confidence: 99%

Parameter Extraction of MOSFETs Operated at Low Temperature

Simoen

Claeys

Martino³

1996

J. Phys. IV France

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Abstract. In this paper, an overview is given of the methods for practical parameter extraction for MOSFETs operated at cryogenic temperatures. The methods considered are based on the input characteristics of the device, from which the charge threshold voltage, the subthreshold slope, the effective mobility, the series resistance and the effective gate length is derived. Whenever possible, the physical basis of the mostly semi-empirical methods will be outlined. Finally, pitfalls and problems, related to low temperature MOSFET characterisation, like transient and freeze-out effects, self-heating, etc, are briefly discussed.

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“…However, the effect of confinement on electron mobility has been widely studied [15], [16]. It was found that intersubband scattering increased when the subband energy spacing for electrons was less than twice the polar optical phonon energy [17], leading to a reduced electron mobility in confined structures.…”

Section: Introductionmentioning

confidence: 99%

Quantum Modeling of Thermoelectric Properties of Si/Ge/Si Superlattices

Bulusu

Walker

2008

IEEE Trans. Electron Devices

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Abstract-Using a nonequilibrium Green's function approach, quantum simulations are performed to assess the device characteristics for cross-plane transport in Si/Ge/Si-superlattice thin films. The effect of quantum confinement on the Seebeck coefficient and electrical transport and its impact on the power factor of superlattices are studied. In this case, decreasing well width leads to an increased subband spacing causing the Seebeck coefficient of the superlattice to decrease. Electron confinement also causes a drastic reduction in the overall available density of states. Results show that confinement effects in the silicon barrier are responsible for a 40% decrease in the electrical conductivity of superlattices where barrier films are thinner by a factor of 1.5. In the same two devices, there is a negligible change in the Seebeck coefficient, which results in a decrease in the power factor corresponding to the decrease in conductivity. This decrease in the electrical performance for superlattices with thinner layers may offset the previously hypothesized gains of highly scaled superlattice structures resulting from reduced thermal conductivity. Simulations of the present superlattice structure at varying doping levels show a decrease in power factor with a decrease in device size parameters.

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Subband structure engineering for performance enhancement of Si MOSFETs

Cited by 104 publications

References 2 publications

On the universality of inversion layer mobility in Si MOSFET's: Part I-effects of substrate impurity concentration

On the universality of inversion layer mobility in Si MOSFET's: Part I-effects of substrate impurity concentration

Parameter Extraction of MOSFETs Operated at Low Temperature

Quantum Modeling of Thermoelectric Properties of Si/Ge/Si Superlattices

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