MOVPE Droplets Heteroepitaxial Growth Model
Sergey Shusterman1, E. Cohen2, N. Elfassy2, D.P. Kumah3, Y. Yacoby4, R. Clarke3 and Y. Paltiel2
Solid State Physics Group, Applied Physics Division, Soreq NRC, Yavne 81800, Israel
Email: [email protected]
Applied Physics Department, Center for nano science and nano technology The Hebrew University, Givat Ram,
Jerusalem 91904, Israel
Applied Physics Program, University of Michigan, 1011 North University Avenue, Ann Arbor, MI 48109, USA
Racah Institue of Physics, Givat Ram, The Hebrew University, Jerusalem 91904, Israel
There is an increasing interest in Quantum Dot (QD) structures for various applications, including
optoelectronic devices, quantum information processing and energy harvesting. Over the last few years, selfassembled QD's, prepared by different methods have been utilized in different semiconductor systems. In
our work we are growing self-assembled QD's, using the Droplet HeteroEpitaxial (DHE) mode.[1] This
method is potentially not limited to mismatched material systems as in other growth methods and is very
attractive for the growth of binary and more complicated compounds based on low melting point elements.
Although the droplet heteroepitaxy method is relatively complex, it is quite relaxed with respect to the
material combinations that can be used. This offers great flexibility in the systems that can be achieved but
also results in complex growth mechanisms.[2] Understanding of the DHE growth dynamics will open a
way to tune the confinement potential, electrical and optical properties of the final nano-structures.
Detailed structural and composition information with sub-nano resolution has been obtained using
both conventional nano characterization methods such as Kelvin Probe AFM techniques and Transmission
Electron Microscopy as well as surface X-ray diffraction methods.[3] The Coherent Bragg Analyses
(COBRA) is a direct x-ray phasing method, enabling to obtain sub angstrom resolution electron density
maps of the dot system.[4] Under different growth conditions and in different QDs systems a number of
interesting phenomena have been observed; such as penetration of the dots into the substrate (“nanodrilling”), inter-diffusion, intermixing of materials, dislocations, etc. The structure and composition of the
final dot may be very different from the one initially intended. [5]
In my talk I will present the structure and composition of a number of quantum dot systems grown by
the DHE method, emphasizing the insights that these experiments provide with respect to the growth
1. N. Koguchi, S. Takahashi and T. Chikyow, J. Cryst. Growth, 111, 688 (1991).
2. K. Watanabe, N. Koguchi and Y. Gotoh, Jpn. J. Appl. Phys. pp. L79-L81 39 (2000).
3. Y. Yacoby, R. Pindak, R. MacHarrie, L. Pfeiffer, L. Berman, R. Clarke, J. Phys: Condens. Matter. 12,
3929 (2001).
4. D. P. Kumah, S. Shusterman, Y. Paltiel, Y. Yacoby, R. Clark, Nature Nanotechnology 4 835 (2009).
5. E. Cohen, S. Yochelis, S. Shusterman, D.P. Kumah, R. Clarke, Y. Yacoby, and Y. Paltiel, Appl. Phys.
Lett. 98, 243115 (2011).