Fabrication of III-V Compound Semiconductor Quantum Nanostructures by Droplet Epitaxy on Lattice Matched Systems

Jong Su Kim^1*, Sang Jun Lee², Jin Dong Song³, Kwangseuk Kyhm⁴, Heedae Kim⁵, Yongmin Kim⁶

¹Department of Physics, Yeungnam University, Gyeongsan 38541, Korea
²Division of Convergence Technology, Korea Research Institute of Standards and Science, Daejeon 34113, Korea
³Post-Silicon Semiconductor Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
⁴Department of Opto-mechatronics, Cogno-mechatronics, Physics Education, Pusan Nat’l University, Busan 609-735, Korea
⁵School of Physics, Northeast Normal University, Changchun 130024, Korea
⁶Department of Physics, Dankook University, Cheonan 31116, Korea

* Presenter:Jong Su Kim

For more than two decades, Stranski-Krastanow (S-K) growth mode and droplet epitaxy (DE) method have been most commonly used for the fabrication of quantum nanostructures (QNs). The DE process has attracted attention for the fabrication of QNs based on group-III droplets formation without group-V supply. The DE method has been an effective way to fabricate quantum dots (QDs) for not only lattice-matched but also lattice mismatched material systems. DE has been used to fabricate various QNs including QDs, coupled QDs (c-QDs), quantum dot molecules (QDMs), single quantum rings (s-QRs), and concentric double QRs (d-QRs). Especially, lattice matched GaAs/AlGaAs QNs, such as QDs, s-QRs, and d-QRs are a good example of systems grown by using DE. The merits of the DE mode are not only to fabricate new-functional QNs, but also to control the density of QDs by using simple process. Geometric complexity of QNs could be applied to investigate the quantum interference effects and fundamental properties of QNs.
In this work, we investigated the droplet epitaxy for the fabrication of QNs on lattice matched hetero-epitaxy. The formation mechanisms of various GaAs QNs on lattice matched system such as a GaAs/AlGaAs are discussed. During the formation of Ga-droplet and subsequent crystallization for QNs, the surface reconstructions were monitored by reflection high energy electron deflection (RHEED). The surface morphology and structural properties of Ga-droplets and various GaAs-QNs were investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM).
During the Ga-molecules supply on to the lattice-matched AlGaAs surface, we discussed the Ga-droplet formation dynamics based on Ga migration and diffusion behavior on GaAs (100), (111)A and (111)B surfaces. We discussed the formation mechanism of GaAs QNs and optical properties.
*e-mail; jongsukim@ynu.ac.kr

Keywords: -