Optical and structural properties of InP quantum dots embedded in(AlxGa1−x)0.51

Abstract

Within this work we present optical and structural properties of InP quantum dots embedded in ͑Al x Ga 1−x ͒ 0.51 In 0.49 P barriers. Atomic force microscopy measurements show a mainly bimodal height distribution with aspect ratios ͑ratio of width to height͒ of about 10:1 and quantum dot heights of around 2 nm for the smaller quantum dot class ͑type A͒ and around 4 nm for the larger quantum dot class ͑type B͒. From ensemblephotoluminescence measurements we estimated thermal activation energies of up to 270 meV for the type-A quantum dots, resulting in a 300 times higher luminescence intensity at 200 K in comparison to our InP quantum dots in Ga 0.51 In 0.49 P at the same emission wavelength. Photon statistic measurements clearly display that InP quantum dots in ͑Al 0.20 Ga 0.80 ͒ 0.51 In 0.49 P emit single photons up to 80 K, making them promising candidates for high-temperature single-photon emitters.

Size dependent carrier thermal escape and transfer in bimodally distributed self assembled InAs/GaAs quantum dots

“…4,6,8,9,11,[17][18][19][20] The thermally activated escape mechanism initiates the temperature dynamics and therefore has deserved a lot of attention in the past. It has been investigated attending to the available final states, i.e., QD excited states, 15,21 wetting layer, 4,6,7,13,20,22 GaAs barrier, 8,9,23 and impurity/defect levels. [23][24][25][26] Thermal escape can be also investigated attending to the nature of the particles being promoted to a higher energy state.…”

“…Whether one or the other is appropriate in a particular sample depends on the barrier height and therefore might vary for QDs of given composition but different size. 13 The QD areal density must be also considered as it might be comparable to the density of traps and defects competing for the same carriers. A superlinear evolution of the integrated intensity at high power excitation has been proposed as a sign of independent electron and hole capture and escape.…”

“…A variety of carrier redistribution effects caused by temperature has been investigated in QD ensembles. [4][5][6][7][8][9][10][11][12][13][14][15] It is commonly accepted that the sigmoidal evolution of the peak energy and full width at half maximum of the PL bands is due to carrier promotion from small QDs to larger ones. 6 Therefore, quantum dot size distributions, carrier capture, relaxation, and re-trapping among QDs of different sizes had to be considered to model correctly the QD recombination dynamics.…”

Thermal effects in InP/(Ga,In)P quantum-dot single-photon emitters

“…19 In InP QDs an upper limit of 80 K has been reached using Al containing barriers. 13 Upon raising temperature the g ͑2͒ ͑0͒ value progressively increases due to the increasing background luminescence. Temperature also influences the antibunching width.…”

“…[7][8][9] InP QDs have received special attention for their potential use as SPEs in the visible range. [10][11][12][13][14][15][16] Photon correlation measurements for both continuous 9,11 and pulsed excitation 11,13,15 as well as under electrical injection 14 show clear antibunching dips in the second-order photon correlation function g ͑2͒ ͑ ͒ at zero delay ͑ =0͒. The standard form of the correlation function is…”