Impact of the non-planar morphology of pre-patterned substrates on the structural and electronic properties of embedded site-controlled InAs quantum dots

Abstract

We present an experimental and theoretical analysis of the influence of a surface nanopattern on the properties of embedded InAs/GaAs quantum dots (QD). In particular, we analyze QDs grown on nanoimprint lithography (NIL) patterned grooves and investigate the influence of the non-planar surface morphology on the size, shape, strain distribution, and electronic structure of the embedded QDs. We show that the height reduction of InAs QDs during GaAs capping is significantly less pronounced for the QDs grown on the pattern than for the self-assembled QDs. Furthermore, the pattern has a strong impact on the strain and composition profile within the QD. The experimentally observed strain distribution was successfully reproduced with a three-dimensional model assuming an inverse-cone type composition gradient. Moreover, we show that the specific morphology of the QDs grown in the grooves gives rise to an increase of the vertically polarized photoluminescence emission which was explained by employing 8-band k.p calculations. Our findings emphasize that the surface curvature of the pattern not only determines the nucleation sites of the QDs but also has a strong impact on their morphological properties including shape, size, composition profile, and strain distribution. These properties are strongly cross-correlated and determine the electronic and optical characteristics of the QDs. V C 2013 AIP Publishing LLC.

GaAs surface passivation for InAs/GaAs quantum dot based nanophotonic devices

“…The radiative decay rate is, in turn, proportional to the projected LDOS ( ) r w Z, , which depends explicitly on the thickness of the cap layer Z and the optical frequency w. We consider only the horizontal dipole orientation, which is the dominant polarization of the InAs QDs [50]. The measured total decay rate for QDs in the investigated inhomogeneous medium can thus be expressed as…”

The dilatation line in an elastic wedge

“…In the past, similar problems were solved by either finite-element method [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] or molecular dynamics simulations [22,[36][37][38] for quantum dots on substrates and in subsurface layers [20][21][22]25,[27][28][29], segmented nanowires [30,31,36], core-shell nanoparticles [33,38] and core-shell nanowires [23,24,26,34,35], and some other nanoheterostructures [32,37]. However, the results of finite element and molecular dynamics modeling are inconvenient to use for constructing general theoretical models aimed at describing misfit stresses and mechanisms of their relaxation in nanoheterostructures.…”

Cavity-enhanced single photon emission from site-controlled In(Ga)As quantum dots fabricated using nanoimprint lithography

“…10 For example, the fabrication of large arrays of SCQDs with tunable properties and high optical quality using a combination of UV-NIL and molecular beam epitaxy (MBE) has been reported. [11][12][13][14][15] However, for practical applications, it is important to obtain high collection efficiency of the emission from/to the QD. This could be achieved by embedding a QD in a photonic microcavity resonant with the QD transition energy, which enhances the directionality of the QD emission.…”