Effect of dimensionality and morphology on polarized photoluminescence in quantum dot-chain structures

Abstract

Change of the photoluminescence (PL) polarization is studied by changing the excitation intensity and temperature for aligned In(Ga)As quantum dot (QD) structures with varying inter-dot distances grown by molecular beam epitaxy on semi-insulating GaAs (100) substrates. An unusual increase of the polarization ratio is observed by increasing the temperature and/or excitation intensity throughout a low temperature (T < 70 K) and low intensity (Iex < 1 W/cm2) range. This increase as well as the general behavior of the polarized PL are the results of the exciton dynamics and the peculiarities of the system morphology. They are due to the varying inter-dot distances which change the system from zero-dimensional comprised of isolated QDs to one-dimensional comprised of wire-like structures.

Structural and magnetic confinement of holes in the spin-polarized emission of coupled quantum ring–quantum dot chains

“…The angular dependence of the emission lines for both QDs and QRs is displayed in the polar plot that shows the normalized PL intensity to its maximum value as a function of the polarization direction. We detected a polarization degree at the maximum of QD and QR emissions of around 10%, for these typical elongated dots [24], as also displayed in Fig. 2(c).…”

Excitation transfer in stacked quantum dot chains

“…QDCs or laterally-coupled QDs have garnered significant interest in the past decade [13] and have recently gained renewed interest due to their unique geometry suitable for fundamental transport studies [14] and polarization-sensitive optoelectronic devices [15]. However, QDCs are rarely studied in stacked forms due to their complex optical characteristics [16], particularly when coupling can simultaneously occur laterally and vertically as is the case here.…”

Deep level centers and their role in photoconductivity transients of InGaAs/GaAs quantum dot chains

“…This luminescence is associated with transitions between the quantum confined states of the InGaAs nanostructures. 29 Also shown in Figure 4(a) is the photocurrent, which was measured with an applied bias of 50 mV over a photon energy range of hv ¼ 0.6-1.8 eV at 290 K. Interband transitions (see arrow 3 in Figure 4(b)) associated with confined states in the nanostructures give rise to a photocurrent component starting from hv % 1.11, 1.16, and 1.12 eV for samples C1, C2, and C3, respectively. These are the threshold energies determined by the intersection of the baseline and the rise due to QDs.…”