Effect of second-order piezoelectricity on the excitonic structure of stress-tuned In(Ga)As/GaAs quantum dots

Abstract

We study the effects of the nonlinear piezoelectricity and the In distribution on the exciton energy, the electron-hole electric dipole moment, and the fine-structure splitting in stress-tunable InGaAs/GaAs quantum dots integrated onto a piezoelectric actuator. In particular, we investigate in detail the contributions of various elements of the expansion of the electrical polarization in terms of externally induced elastic strain on the latter two important quantum dot properties. Based on the comparison of the effects of first-and second-order piezoelectricity we provide a simple relation to estimate the influence of applied anisotropic stress on the quantum dot dipole moment for quantum dots significantly lattice mismatched to the host crystal.PACS numbers: 78.67. Hc, 73.21.La, 85.35.Be, 77.65.Ly Semiconductor Quantum dots (QDs) provide a number of appealing applications. Among others, QDs may be used as gain materials for lasers, 1-3 as single photon emitters for optical fibre communication, 4 as building blocks of secure optical links using entangled photon pairs, 5 for quantum gates, 6,7 or are used in biomedical applications. 8 The capability of QDs to confine the motion of electrons and holes in all three spatial dimensions offers the advantages of a discrete, atom-like electronic system 9 within a solid-state platform. The strong confinement and the Coulomb interaction among trapped charge carriers promotes the formation of stable few-particle states 10 like neutral exciton (X) and biexciton (XX) whose cascaded radiative recombination allows the generation of single-and entangled photons. 11,12 The application of QDs as quantum light sources in advanced quantum communication and computation schemes 13,14 demands well-defined transition energies, vanishing finestructure splitting (FSS) and extensive control over the QDs' interaction with the charge environment. In this regard, the statistical distribution of structural parameters such as size, shape, or composition of self-assembled QDs 15 , which becomes apparent via deviations of essential emission properties among different QDs, represents a major challenge towards application and demands for effective methods for (reversible) post-growth engineering 16 of the electronic structure of individual QDs.In this context, externally applied stress mediated via piezoelectric actuators 17 has proven to be an effective tool to (simultaneously) tune transition energies 18 and FSS 5,19 , thus, enabled interference experiments with photons from remote QDs 20 or the extraction of high-fidelity polarization-entangled photons. 21 In a recent work 22 we moreover demonstrated that applied stress allows to control magnitude and alignment of the vertical electronhole separation in In(Ga)As QDs manifesting itself via a built-in dipole moment (p) along the growth direction. p is commonly present in as-grown QDs 23 and its interaction with charges in their vicinity leads to spectral diffusion 24 causing an inhomogeneous linewidth broadening of the corresponding optical tra...

Electronic states of (InGa)(AsSb)/GaAs/GaP quantum dots

“…Piezoelectricity is defined as the generation of electric polarization by the application of stress to a crystal lacking a center of symmetry [62]. Following our previous works [27,53,63], we calculate the piezoelectric polarization (P) in first (P l ) and second (P nl ) order [64,65]…”

Structural and compositional analysis of (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots

“…Optoelectronic devices with self-assembled quantum dots (QDs) as an active medium have shown superior properties in many applications, such as semiconductor lasers 1 , 2 , single and entangled photon emitters 3 – 12 , solar cells 13 , and quantum information technology 14 – 19 . Antimony-based type-II QDs 20 – 25 that exhibit hole confinement are especially suitable for memory applications: the so-called QD-Flash memories 25 – 27 .…”

Modeling electronic and optical properties of III–V quantum dots—selected recent developments

“…Bester et al 26 investigated the effect of the quadratic terms on circular-shaped QDs and discovered that they compensate the first-order field inside the QD, resulting in a potential-free QD. Later, the research was expanded to include more realistic morphologies such as truncated pyramids and uneven alloyings 27 – 29 .…”