Monte Carlo study of diffusion phenomena in III - V modulation doped heterostructures

Sleiman, A.; Thobel, Jean-Luc; Bourel, P.; Dessenne, F.; Fauquembergue, R.

doi:10.1088/0268-1242/12/1/014

Cited by 8 publications

(5 citation statements)

References 19 publications

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“…Moreover, the D n = kt/qµ n equality cannot be satisfied. The dotted curve represents the calculated Early voltage where mobility and the longitudinal diffusion constant are obtained by accounting for non-stationary transport [20] and the agreement with experimental data is quite good. In the inset the calculated Early voltage is compared with the data reported by Hayes et al [19] for a graded SHBT with N DE = 2 × 10 17 cm −3 , N AB = 2 × 10 19 cm −3 and N DC = 3 × 10 16 cm −3 with a base width of 0.25 µm and a graded layer thickness of 60 nm, and the agreement is excellent.…”

Section: Resultsmentioning

confidence: 53%

Effect of surface recombination on the Early voltage in HBTs

Chiu

Anwar

1999

Semicond. Sci. Technol.

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The effect of surface recombination on the Early voltage in heterojunction bipolar transistors (HBTs) is presented. Calculations are based by invoking the partitioning of the total current into thermionic and tunnelling components. The tunnelling current is computed by using an exact quantum mechanical calculation. Narrow-base HBTs are simulated by taking into account non-stationary transport in the base. Surface recombination degrades the Early voltage in a uniformly doped base. In an exponentially doped base a scaled-down base width modulation results in a higher Early voltage. At high base doping levels, the Early voltage is further degraded by neutral base recombination. Theoretical results are compared with experimental data and the agreements are excellent.

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Section: Resultsmentioning

confidence: 53%

Effect of surface recombination on the Early voltage in HBTs

Chiu

Anwar

1999

Semicond. Sci. Technol.

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“…In the high-field region, one can see a strong decrease of diffusivity with the field. The behaviour of the diffusivity-field characteristics in this region is associated with intervalley transfers [5,21].…”

Section: Resultsmentioning

confidence: 94%

Oleg Matveevich Nefedov

2006

Russ. Chem. Rev.

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Standard Monte Carlo methods for calculating diffusivity fail when the degeneracy of the electron gas is important. We apply a recently proposed Monte Carlo procedure in order to study diffusion coefficients in degenerate bulk GaAs at 77 K. Two sets of electrons are simulated, the first one representing the uniform 'background' electron density and the second one accounting for additional 'excess' electron concentration. The diffusion coefficients are calculated accounting for 'excess' electrons only. We compare the results obtained using this method with those obtained using the standard technique. We report diffusivity-field characteristics for several electron concentrations. Obtained zero-field values are in good agreement with those predicted by the Einstein relation. We found that, in the low-field region, diffusion coefficients evolve quite slowly with the electric field and the isotropy is conserved.

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“…We have placed the alloy fraction x and U outside the integral although they are compositionally dependent, and hence spatially dependent. Previous work [9][10][11][12], has used the same approach for lattice-matched InGaAs/InAlAs quantum well systems. It is in the same spirit as for the phonon scattering rates, where both the effective mass and the deformation potential, which are position dependent within a heterostructure, are placed outside the integral [3,[32][33][34].…”

Section: Random Alloy Scatteringmentioning

confidence: 99%

“…The use of the InGaAs material system has become increasingly widespread in FETs and other high-speed communication devices, due to its high low-field mobility by virtue of its small effective mass and large -L separation compared with GaAs. There has been some previous theoretical work to study high-field electron transport, using Monte Carlo simulations in InGaAs/InAlAs quantum wells [9][10][11][12]. All these studies were based on lattice-matched In 0.53 Ga 0.47 As/In 0.52 Al 0.48 As quantum wells and addressed modulation-doped heterostructures.…”

Section: Introductionmentioning

confidence: 99%

“…However, to the authors' knowledge this is the first time that a theoretical study has been made of carrier transport in delta-doped InGaAs/InAlAs quantum wells, either lattice-matched or strained. The technique used here to investigate electron transport is similar to that used in [3,5,[9][10][11][12]. Real space transfer into the barriers is included in these simulations.…”

Section: Introductionmentioning

confidence: 99%

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Monte Carlo simulation of electron transport in delta-doped lattice-matched and strained-balanced InGaAs/InAlAs quantum wells

Watling

Walker

Harris

et al. 1999

Semicond. Sci. Technol.

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Strained-balanced In x Ga 1−x As/InAlAs quantum well structures have been shown to generate high carrier density, high-mobility layers suitable for power field effect transistor (FET) applications. Doped channel devices allow higher carrier densities than modulation-doped structures but with reduced carrier velocities due to increased ionized impurity scattering. The amount of ionized impurity scattering may be reduced by the introduction of compositional grading in In x Ga 1−x As quantum wells which results in an increasing depth of the quantum well on the opposite side to the delta-doped plane. The grading is achieved by the use of a number of steps, where each step has a fixed value of x. An ensemble Monte Carlo simulation has been used to calculate the velocity-field characteristics of the conduction electrons confined within the quantum well in such a structure. Here the envelope wavefunctions for the confined electrons are calculated using a self-consistent Poisson-Schrödinger solver. Our velocity-field characteristics show good agreement with experiment for the three-step structure but the agreement is noticeably worse for lattice-matched and five-step structures. We have shown that a correlation between the low-field mobility and saturation velocity observed experimentally for GaAs/AlGaAs and In x Ga 1−x As quantum wells and theoretically for GaAs/AlGaAs quantum wells is also valid for the predicted results in these structures. A similar explanation to that provided for the GaAs/AlGaAs quantum wells is shown to hold here.

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Monte Carlo study of diffusion phenomena in III - V modulation doped heterostructures

Cited by 8 publications

References 19 publications

Effect of surface recombination on the Early voltage in HBTs

Effect of surface recombination on the Early voltage in HBTs

Oleg Matveevich Nefedov

Monte Carlo simulation of electron transport in delta-doped lattice-matched and strained-balanced InGaAs/InAlAs quantum wells

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