R. Eppenga

Philips (Netherlands)

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Effects of band mixing on the radiative properties of a quantum well

Fiber & Integrated Optics (1988)

R. Eppenga S. Colak M. F. H. Schuurmans

Abstract The effect of band mixing and non-parabolicity on quantum well gain and spontaneous emission is studied using k.p theory. Spectra of gain and spontaneous emission are strongly modified but the relation of maximum gain versus nominal current density is not strongly affected.

Amplified spontaneous emission

10.1080/01468038808219352

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Citations (0)

Electric fields and valence-band offsets in n+n [001] and [110] ZnSe/GaAs, GaAs/Ge, and ZnSe/Ge superlattices

Physical review. B, Condensed matter (1989)

R. Eppenga

Results for n+n [001] and [110] (n=1--5) ZnSe/GaAs, GaAs/Ge, and ZnSe/Ge superlattices obtained from self-consistent calculations with the augmented-spherical-wave ab initio band-structure method are presented. The valence-band offsets are calculated with the frozen-potential method and compared with those obtained with a new method that is based on the shifts of the potentials of the individual atoms. The internal electric fields that result from the charge separation at the interfaces in the polar [001] superlattices is calculated, and its origin is traced. The valence-band offset is shown to be not affected by these fields.

Band offset

10.1103/physrevb.40.10402

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Citations (30)

Effect of bulk inversion asymmetry on [001], [110], and [111] GaAs/AlAs quantum wells

Physical review. B, Condensed matter (1988)

R. Eppenga M. F. H. Schuurmans

The spin splitting of the conduction band due to the inversion asymmetry of the microscopic crystal potential is predicted to depend linearly on the components of the parallel wave number ${\mathrm{k}}_{\ensuremath{\parallel}}$ for small ${k}_{\ensuremath{\parallel}}$ in undoped GaAs/AlAs quantum wells. The linear dependence is due to the quantization of the confinement levels; the bulk spin splitting depends cubically on $\mathrm{k}$. We have calculated the splitting both numerically and analytically for GaAs/AlAs quantum wells grown along the [001], [110], and [111] directions. In the linear regime the average spin splitting is shown to be about a factor of 2 smaller for [110] quantum wells than for [001]- and [111]-grown quantum wells. The splitting is calculated to be $\ensuremath{\Delta}E=4$ meV at ${k}_{\ensuremath{\parallel}}=0.07(\frac{2\ensuremath{\pi}}{a})$ for a 25-\AA{} [001]-grown GaAs/AlAs quantum well.

Energy level splitting

10.1103/physrevb.37.10923

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Citations (135)

Oscillating Transverse Voltage in a Channel with Quantum Point Contact Voltage Probes

NATO ASI series. Series B : Physics (1991)

L. W. Molenkamp H. van Houten C. W. J. Beenakker R. Eppenga C. T. Foxon

10.1007/978-1-4684-1348-9_26

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Electron-beam collimation with a quantum point contact

Physical review. B, Condensed matter (1990)

L. W. Molenkamp A. A. M. Staring C. W. J. Beenakker R. Eppenga C.E. Timmering

Collimation of the electron beam injected by a point contact in a two-dimensional electron gas is demonstrated using a geometry with two opposite point contacts as injector and collector. The collimation is maintained over a distance of at least 4 \ensuremath{\mu}m, and is destroyed by a small magnetic field. The inferred collimation factor scales linearly with the point-contact resistance, as predicted by the semiclassical theory.

Collimated light

Semiclassical physics

Interaction point

10.1103/physrevb.41.1274

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Citations (155)

Low-frequency noise of quantum point contacts in the ballistic and quantum Hall regime

Physica B Condensed Matter (1991)

F. Liefrink A.J. Scholten Cees Dekker R. Eppenga H. van Houten

Conductance quantum

Quantum noise

Ballistic conduction

10.1016/0921-4526(91)90714-p

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Citations (24)

Band mixing effects on quantum well gain

IEEE Journal of Quantum Electronics (1987)

S. Colak R. Eppenga M. F. H. Schuurmans

Gain in a quantum well is studied by using the optical matrix elements and the band structure computed by the k \cdot p method within the envelope function approximation. Due to band mixing, the k \cdot p method gives nonparabolic bands which affect both the minimum confinement energies and the density of states functions. The density of states functions are found to differ considerably from the simple step-like shape computed from the band edge effective masses. The band mixing also results in large differences in the momentum vector dependence of the matrix elements, and moreover, some of the transitions which were previously assumed to be forbidden become partially allowed. The quantum well gain spectra calculated by the k \cdot p method and the k -selection rules clearly show the effects of band mixing both in shape and in peak magnitude. These results are considerably different than those obtained from the conventional methods which consider an effective mass electron (or hole) in a finite one-dimensional potential well with parabolic bands and with matrix elements which have constant total magnitude. A practical conclusion which is reached from these comparisons is that the threshold excitation in a quantum well laser is found to be strongly underestimated if band mixing effects are ignored.

Envelope (radar)

Matrix (chemical analysis)

10.1109/jqe.1987.1073466

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Citations (68)

A New Approach to the Quantum Hall Effect

Springer series in solid-state sciences (1987)

R. Woltjer R. Eppenga M. F. H. Schuurmans

Maxima and minima

Thermal Hall effect

Sample (material)

10.1007/978-3-642-83114-0_16

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Citations (6)

Possibility of green light emission from GaP/AlP (001) superlattices

Journal of Luminescence (1987)

M. F. H. Schuurmans H. W. A. M. Rompa R. Eppenga

Light emission

10.1016/0022-2313(87)90209-2

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Citations (19)

Spontaneous resistance switching and low-frequency noise in quantum point contacts

Physical Review Letters (1991)

Cees Dekker A.J. Scholten F. Liefrink R. Eppenga H. van Houten

The kinetics of charge transport in quantum point contacts has been studied by low-frequency noise spectroscopy. Temperature and frequency (Lorentzian and 1/f) dependences of the noise spectral density are found to vary strongly from device to device, but the low-T conductance dependence universally exhibits a strong quantum size effect. Based on the direct observation in the time domain of spontaneous resistance switching, the noise is identified to be due to trapping processes which affect the local electrostatic potential. A model is presented which explains the main experimental observations.

Quantum noise

10.1103/physrevlett.66.2148

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Citations (97)