Phonon-limited near equilibrium transport in a semiconductor superlattice

Palmier, J.F.; Chomette, A.

doi:10.1051/jphys:01982004302038100

Cited by 65 publications

(11 citation statements)

References 15 publications

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“…11 Furthermore, for 2ϫ2 ordered SL, the localized-state hopping model may no longer hold, and the continuous-energy miniband scattering model might be more relevant. 12 If that is the case, then the diffusion constant of the 2ϫ2 o-SL could be one or two orders of magnitude larger than the values from Ref. 11 for the 7ϫ7 o-SL.…”

Section: Figures 3 and 4 Show The Energy E(t)mentioning

confidence: 79%

“…We included the electron-phonon interactions suggested to be important by previous studies on quantum well transport. [9][10][11][12] The particular d-SL that we consider here is the one grown by Sasaki: 2 starting from an ordered SL (o-SL͒ ͑AlAs͒ 2 ͑GaAs͒ 2 , we replace at random two-ML-thick segments by one-or three-ML-thick segments, thus creating a disordered chain with randomly selected equal-probability layer thicknesses of nϭ1,2,3. In order to simulate the breaking of translational symmetry along the growth axis z, we have used unit cells with a total of 2000 randomly selected ML.…”

Section: Introductionmentioning

confidence: 99%

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Direct calculation of the transport properties of disordered AlAs/GaAs superlattices from the electronic and phonon spectra

Wang

Zunger

Mäder³

1996

Phys. Rev. B

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We have calculated from first principles the recently measured electron and hole transport of disordered AlAs/GaAs superlattices, in which the individual layer thicknesses n,m,nЈ,mЈ,. .. of sequence ͑AlAs͒ n ͑GaAs͒ m ͑AlAs͒ n Ј ͑GaAs͒ m Ј. .. are 1, 2, or 3, selected at random with equal probabilities. First, the near-edge electronic states are calculated using a three-dimensional pseudopotential representation for a ϳ2000-ML cell. The results are then modeled by an effective-mass approximation, thus obtaining the electronic states in a wider energy range. All electronic states are found to be localized in the superlattice direction. Second, the phonon-assisted-hopping probabilities between different localized electronic states are calculated from first principles, including contributions of polar optical, acoustic deformation-potential, and acoustic piezoelectrical effects. Third, the master equation describing electron transport via phonon-assisted hopping is addressed using Monte Carlo simulations. The resulting transport properties versus temperature are analyzed according to dispersive transport theories, including the crossover from dispersive to equilibrium transport. A simple model for the photoluminescence process is proposed on the basis of the transport calculations. Our results agree qualitatively with recent experimental data.

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Section: Figures 3 and 4 Show The Energy E(t)mentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Direct calculation of the transport properties of disordered AlAs/GaAs superlattices from the electronic and phonon spectra

Wang

Zunger

Mäder³

1996

Phys. Rev. B

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“…9 This explains the strong decrease in the observed photocurrent amplification as the superlattice barriers were made thicker.…”

Section: New Quantum Photoconductivity and Large Photocurrent Gain Bymentioning

confidence: 93%

New Quantum Photoconductivity and Large Photocurrent Gain by Effective-Mass Filtering in a Forward-Biased Superlatticep−nJunction

et al. 1985

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We report a new quantum-type photoconductivity in a forward-biased p + -n junction with a superlattice in the n layer. This novel phenomenon is characterized by several striking features: a high photocurrent gain ( -7 x 10 3 ), accompanied by a blue shift in the spectral response and a reversal in the direction of the photocurrent, when the forward bias exceeds the built-in potential. Photoconductive gain is caused by the large difference in the tunneling rates of electrons and holes through the superlattice layers, due to their large mass difference (effective-mass filtering). This is the first time that photoconductive gain is observed in a p-n junction.PACS 73.40.Lq Photoconductivity is a widespread phenomenon in semiconductors. If the lifetime of the photogenerated carriers exceeds their transit time, photoconductivity is accompanied by current gain. 1 The gain and associated gain-bandwidth product are therefore controlled by bulk properties such as carrier mobilities and lifetimes. In this Letter we report a new photoconductivity of quantum mechanical origin, accompanied by a very large photocurrent amplification, in a forward-biased superlattice p-n junction.The heterostructure, grown by molecular-beam epitaxy, consists of a p + -n junction grown on a 1-^m-thick n + ( = 2x 10 18 cm" 3 ) Gao.47Ino.53As buffer layer, lattice matched to a (100) n + InP substrate. The undoped n layer (n = 1 x 10 15 -1 x 10 16 cm" 3 ) comprises 100 23-A-thick Al 0 48 In 0 .52As barriers alternated with 100 49-A-thick Gao.47Ino.53As wells. Transmissionelectron-microscopy studies indicate that the interfaces are abrupt to better than two monolayers. The top p + region is 1 /xm thick and doped to -2xl0 18 cm" 3 . The mesa diodes (area = 1.3xl0~4 cm 2 ) had excellent forward and reverse I-V characteristics. From capacitance-voltage measurements the carrier concentration (rt-type) in the superlattice region was found to decrease monotonically from 2xl0 16 /cm 3 (at a distance of 0.2 /xm from the p + -n heterointerface) to 4 xl0 14 /cm 3 near the interface with the n + layer. The built-in potential determined from both C-Kand I-V measurements is 0.65 V. The optical power incident on the detector was kept low ( -1 nW); the shortcircuit photocurrent was measured by a 181 PAR current-sensitive preamplifier followed by a 5604 PAR lockin. Figure 1 shows the responsivity (photocurrent/ divided by incident optical power) at 70 K as a function of forward bias voltage at a wavelength of 1.2 /xm and a chopping frequency of 1 kHz. The responsivity exhibits a relatively flat portion at low bias and then a rapid (roughly exponential) falloff at voltages greater than 0.4 V. This represents the standard behavior of the photocollection efficiency in forward-biased p-n junctions. 2 The responsivity reaches a minimum at a forward bias equal to the built-in potential (0.65 V). Above this voltage the responsivity takes off rapidly and increases by about five orders of magnitude within 0.2 V, indicating the presence of a current gain mechanism. The hi...

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“…We reserve for another paper the mathematical details and a more complete presentation of the exact calculation. The procedure used to compute the collision time or S(f) can be found in [6] respectively for polar optical phonon scattering and acoustical deformation potential scattering. For interface scattering we make use of the Dharssi-Butcher model same as advanced in section 2, namely the distorsion of the free trajectories with only a marginal effect of the nature of scattering mechanisms.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

Optical tomograph with photon counting and projective reconstruction of the parameters of absorbing 'phantoms' in extended scattering media

1999

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A semi-classicai theon, of the non-linear miniband condLction n crossed electric and magnetic fields is presented The Bo.tzmann transport equation is solved with realrstic scattering mechanisms. i.e. electron-phonon scartering and interface potent al fluctuat;ons. The technique conssts of a characteristic solation of tne electron dynamics along tne free trajectories associated with an terative convergent algorithm. The main effect of the transverse magnetic field is interpreted n the frame of the Esaki-Tsu model by the modification of the free trajectories by the Lorentz force which repels t h e onset of Bragg scattering to higher electric f elds A direct comparison W th experimentalcurrent-voltage data is performed in taking into account the electric field inhomogeneity. Free trajectories in k-space

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Phonon-limited near equilibrium transport in a semiconductor superlattice

Cited by 65 publications

References 15 publications

Direct calculation of the transport properties of disordered AlAs/GaAs superlattices from the electronic and phonon spectra

Direct calculation of the transport properties of disordered AlAs/GaAs superlattices from the electronic and phonon spectra

New Quantum Photoconductivity and Large Photocurrent Gain by Effective-Mass Filtering in a Forward-Biased Superlatticep−nJunction

Optical tomograph with photon counting and projective reconstruction of the parameters of absorbing 'phantoms' in extended scattering media

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