Type-II InAs/GaAsSb/GaAs Quantum Dots as Artificial Quantum Dot Molecules

Abstract

We have studied theoretically the type-II GaAsSb capped InAs quantum dots for two structures differing in the composition of the capping layer, being either (i) constant or (ii) with Sb accumulation above the apex of the dot. We have found that the hole states are segmented and resemble the states in the quantum dot molecules. The two-hole states form singlet and triplet with the splitting energy of 4 µeV / 325 µeV for the case (i) / (ii). We have also tested the possibility to tune the splitting by vertically applied magnetic field. As the predicted tunability range was limited, we propose an approach for its enhancement.

Optical response of (InGa)(AsSb)/GaAs quantum dots embedded in a GaP matrix

“…The growth and the physical properties of III-V quantum dots (QDs) have been extensively studied, leading to a variety of appealing applications, especially in semiconductor opto-electronics. Such QDs are crucial for classical telecommunication devices as for low threshold/high bandwidth semiconductor lasers and amplifiers [1][2][3][4][5], and for single photon and entangled photon pair emitters for quantum communication [6][7][8][9][10][11][12][13][14][15], among other quantum information technologies [16][17][18][19][20][21][22][23]. Most of the present applications in optics are based on socalled type-I QDs, which show direct electron-hole recombination in both real and k-space, as for In(Ga)As QDs embedded in a GaAs matrix.…”

“…Much less attention has been given to type-I indirect and/or type-II QDs, particularly antimony-based ones, like In(Ga)As QDs overgrown by a thin Ga(AsSb) layer [24][25][26][27][28], or In(Ga)Sb QDs in a GaAs matrix [29][30][31][32][33], which show spatially indirect optical transitions. Such structures generally require more challenging growth processes, but bring new and improved characteristics, for example intense room temperature emission [34], naturally low fine-structure splitting (FSS) [35], increased tuneability of the exciton confinement geometry and topology [22,[36][37][38], radiative lifetime [39,40] and magnetic properties [41][42][43].…”

Excitonic fine structure of epitaxial Cd(Se,Te) on ZnTe type-II quantum dots

“…Mainly semiconductor type-I QDs where both electron and hole wavefunctions are bound inside QD body, show excellent optical properties combined with their compatibility with current semiconductor processing technology and, moreover, they offer the potential for scalability [1][2][3][4][5][6][7][8]. QDs currently cover a rather wide range of topics, from quantum cryptography protocols [9,10], sources of polarization-entangled photon pairs [11][12][13], quantum key distribution [14,15], quantum gates [16][17][18][19][20], or as nanomemories [18,[21][22][23][24][25][26].…”

On the importance of antimony for temporal evolution of emission from self-assembled (InGa)(AsSb)/GaAs quantum dots on GaP(001)

“…Advantages in this respect led to a number of different applications, such as active media in semiconductor lasers [1][2][3], as building blocks for quantum information devices, particularly for quantum repeaters [4][5][6], as efficient single and entangled photon sources [7][8][9][10][11][12][13][14][15], including highlyentangled states for quantum computing [16][17][18][19], or as nanomemories [20][21][22][23][24]. Among III-V QDs, particularly type-I indirect (InGa)(AsSb)/GaAs QDs embedded in a GaP(001) matrix [25,26] have recently attracted attention due to their promising use as storage units for the QD-Flash nanomemory cells [25,26], as potentially effective entangled photon sources [27], owing to their smaller fine-structure splitting (FSS) of the ground state exciton compared to well-known type-I systems such as (InGa)As/GaAs [13,14], and as quantum gates [27][28][29][30]. The concept of hole storage QD-Flash was ini-tially suggested by Bimberg and coworkers [20][21][22][23][24]31] following first pioneering studies [31] regarding the ...…”