Electron and hole spins in InP/(Ga,In)P self-assembled quantum dots

Abstract

The properties of electron and hole spins in InP/(Ga,In)P self-assembled quantum dots are studied through their coherent dynamics using time-resolved Kerr rotation. From these studies information about the g factor and dephasing of the spin excitations is extracted. The electron spin shows a behavior similar to that of electron spins in quantum dots of different material: The g factor is isotropic in the dot plane and with increasing applied magnetic field the spin dephasing accelerates due to variations in the dot ensemble. On the other hand, the hole spin demonstrates a behavior different from other dot systems. Namely, the signal decay on a time scale of about 100 ps does not depend on magnetic field, and the g factor is isotropic in the dot plane. These findings underline previous suggestions that only the electrons are well localized in the InP/(Ga,In)P quantum dots, while the holes are weakly confined and carry bulklike character.

Spin beats in the photoluminescence polarization dynamics of charged excitons in InP/(In,Ga)P quantum dots in presence of nuclear quadrupole interaction

“…The electron gfactor value, |g e | = 1.43, is determined from the slope of this linear dependence using hν = µ B |g e |B. It agrees with the value obtained in [11], while it differs from the value of 1.6 obtained in other studies [20,21]. However, if the nuclear field is pinned along the growth axis, the oscillation frequency will be proportional to B 2 + B 2 N , see the dashed line in the inset of Fig.…”

Electron and holegfactors in InAs/InAlGaAs self-assembled quantum dots emitting at telecom wavelengths

“…In semiconductors, electrons are quasiparticles and their g factor might be drastically different from the g 0 ≈ 2 of a free electron. g factors in QDs have been measured either electrically [4][5][6][7][8][9][10][11] or optically [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. The most widespread optical method is the measurement of the Zeeman splitting in magnetoluminescence spectra which, in general, gives only the exciton g factor [12][13][14][15][16][17][18].…”

“…Other optical methods of g factor determination are spin noise spectroscopy [25] and spin-flip Raman scattering [26]. Especially high precision in the measurement can be achieved with optical pump-probe spectroscopy, where the g factor is determined from the frequency of spin polarization oscillations in a perpendicular magnetic field [19][20][21][22][23][24]. Pump-probe spectroscopy allows one to determine separately the electron and hole g factors as well as the g factor spread, which contributes to the decay of * vasilii.belykh@tu-dortmund.de the oscillations [20].…”

Limited accuracy of conduction band effective mass equations for semiconductor quantum dots

“…The Roth-Lax-Zwerdling formula has the advantage that the fundamental band gap E g , instead of being calculated at some level of approximation to the k k k· p p p theory, can be taken from experiment [43][44][45] . While the standard Roth-Lax-Zwerdling formula is linked to the 8-band k k k· p p p Hamiltonian via a diagonal and parabolic approximations, the full effective mass Hamiltonian accounts also for non-parabolicity corrections and the full structure of the vb.…”

“…(3) The value used for the band gap in the previous approach is still a crude approximation since the actual energy spacing between the states in the conduction and valence bands in a QD are affected by spatial confinement. A common approach, taken in many cases [43][44][45] to estimate the electron g-factor when interpreting experimental data, is to use the measured value of the fundamental transition energy E (exp) g as the effective band gap value for a given system. In our numerical study this corresponds 7/13 (1) Figure 1.…”