Novel Morphologies of InAs Quantum Dot Growth on GaAs Surfaces Containing Nanostructures Formed by Droplet Epitaxy
- PDF / 2,846,609 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 15 Downloads / 214 Views
0959-M08-02
Novel Morphologies of InAs Quantum Dot Growth on GaAs Surfaces Containing Nanostructures Formed by Droplet Epitaxy J.H. Lee1, Zh. M. Wang2, B.L. Liang1, K. Sablon1, N. W. Strom1, and G. J. Salamo2 1 Microep, University of Arkansas, 226 Physics Building, Microep Univ of Arkansas, Fayetteville, AR, 72701 2 Department of Physics, University of Arkansas, Department of Physics, University of Arkansas, Fayetteville, AR, 72701
ABSTRACT Self-assembled InAs quantum dot clusters (QDCs) and InGaAs QD molecules (QDMs) have been demonstrated through a growth technique called “droplet epitaxy” by molecular beam epitaxy (MBE). For QDCs, the size and density of QDs can be controlled with variation of InAs monolayer coverages. For QDMs, Ga contribution from GaAs mound with the interaction of InAs deposition resulted in various number of InGaAs QDs per GaAs mound, ranging from 2 to 6 (bi-QDMs to hexa-QDMs) depending on the specific InAs monolayer deposition. High step density on sidewall of GaAs mound and anisotropy of surface diffusion gave a rise to preferential formation of InAs and InGaAs QDs around GaAs mounds. This hybrid growth approach combining droplet epitaxy and typical QD growth is relatively simple and flexible and doesn’t require further ex-situ surface preparation. This approach of QD arrangement can find applications in optoelectronics as well as physical study of QD interaction.
INTRODUCTION Self-assembly of quantum dots (QDs) has drawn a great deal of attention in the past 15 years due to their unique physical properties and potential applications, such as, quantum computation and various QD based devices and technologies [1-3]. In a typical StranskyKrastanov (S-K) growth mode of self-assembled nanostructures, QDs are formed through the deformation of surface due to coherent strain relaxation [4-5]. Therefore, the S-K growth mode is based on lattice mis-match between substrate and growing films. Although QDs can successfully be fabricated though S-K growth mode, there is a need for different growth approach for the growth of lattice matched nanostructures under inefficient or no lattice mismatch such as GaAs/GaAs and GaAs/AlxGa1-xAs. Droplet epitaxy has been introduced by N. Koguchi et. al., a Japanese group, for this matter [6]. In Ga droplet epitaxy, molecular beam of Ga is applied to surface under no As4 flux. This applied atomic Ga forms liquid droplets on the surface. Then, liquid Ga droplets can be crystallized though an interaction with As4 flux. During this crystallization process, the liquid Ga droplets can take various forms. GaAs single and double ring-like nanostructures and InAs QD formation have been demonstrated by using droplet epitaxy [7-8]. In this paper, we demonstrate the growth of InAs quantum dot clusters (QDCs) and InGaAs quantum dot molecules (QDMs) around GaAs nano-mounds on GaAs (100) substrates.
Since the S-K mode based QDs, however, results in a random spatial distribution, droplet approach was used to grow arrangements of QDs: QDCs and QDMs. The preferential formation of
Data Loading...
