book of abstracts - IM2NP

A B S T R A C T S THURSDAY, JULY 1 N A N O S E A 2 0 1 0
Room Calendal
9H00-9H40
Directed-Self-Ordering of Semiconductor Quantum Nanostructures Grown on
Nonplanar.
Eli Kapon (EPFL SB IPEQ LPN, PH D3 425 (Bâtiment PH), Station 3CH-1015 Lausanne, Switzerland).
Spontaneous nucleation and self-ordering of semiconductor quantum nanostructures such as quantum wires
(QWRs) and quantum dots (QDs) has been extensively studied and employed in investigations of the
properties and applications of these systems in electronics and photonics. Since the size, composition and
environment of these nanostructures fundamentally determine their physical properties, the absence of
structural control renders them of little use in deterministic quantum nanostructure systems.
An alternative approach is that of directed-self-ordering, in which the nucleation and formation of the
nanostructures can be tailored for specific designs. An example of such approach is epitaxial growth on
patterned, nonplanar substrates. Here, a non-planar surface template serves to define the location where
QWRs and QDs form. Such technique is particularly useful when the surface templates evolves in a selflimiting
fashion. This is the case of metal-organic vapor phase epitaxy (MOVPE) on pre-patterned
substrates, in which growth rate anisotropy and nano-capillarity play a fundamental role [1].
This approach yields high quality, site-controlled (In)GaAs/(Al)GaAs V-groove QWR and pyramidal QD
systems. High-uniformity, regular arrays of these structures (e.g., pyramidal QDs with ~1meV
inhomogeneous broadening) have been demonstrated [1,2]. The confining potential of these wires/dots can
be controlled by thickness and /or composition adjustment, like in conventional quantum well structures.
Capillarity-driven alloy segregation in the pyramidal structures provides the possibility of constructing novel
QWR-QD assemblies (e.g., QD molecules) showing novel optical properties [3]. The high symmetry of the
pyramidal QDs, grown on the (111)B substrates, yields unique excitonic features such as vanishing fine
structure splitting, resulting in efficient emission of entangled photons [4]. The excellent site- and emission
wavelength control facilitates integration with optical microcavities for applications in quantum information
processing and ultra-low-threshold nano-lasers [5].
References:
1. G. Biasil and E. Kapon, Phys. Rev. Lett. 81, (1998).
2. M. Felici et al., Small 5, 938 (2009); A. Mohan et al., Small, 2010 (in print).
3. Q. Zhou et al., Small 5, 329 (2009).
4. A. Mohan et al., Nature Photonics, March 2010.
5. P. Gallo et al., Appl. Phys. Lett. 92, 63101 (2008); K. Atlasov et al., Opt. Express 17,18178 (2009).
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