| AVS 55th International Symposium & Exhibition | |
| Thin Film | Thursday Sessions |
| Session TF-ThM |
| Session: | Evaporation, Pulsed Laser Deposition, and Molecular Beam Epitaxy |
| Presenter: | S.G. Choi, National Renewable Energy Laboratory |
| Authors: | S.G. Choi, National Renewable Energy Laboratory Y. Yan, National Renewable Energy Laboratory B.D. Schultz, International Technology Center C.J. Palmstrom, University of California, Santa Barbara |
| Correspondent: | Click to Email |
Incorporation of rare-earth group-V (RE-V) compounds into III-V semiconductors has generated considerable interests as a result of their potential applications in thermodynamically stable metallic contacts to III-V semiconductors and metal-based novel electronic devices. It has recently been demonstrated that RE-V’s in a nanocrystal (NC) form embedded in III-V semiconductor matrix can extend their applications to advanced photonic devices and high-efficiency thermoelectric devices.1,2 High device performance relies upon the synthesis of heterostructures in a controlled manner, and therefore a good understanding of the structure for the growth front is of great importance. Even though early growth studies have shown that the formation of RE-V’s on III-V semiconductors is not associated with any of the typical growth modes, details of their unique growth nature were not discussed until recently.3,4 Our in-situ surface studies on ErAs/GaAs3 and ErSb/GaSb4 systems suggest that the incoming Er atoms displace the Ga atoms in the substrate and form ErAs and ErSb nanocrystals “within” the substrate surface rather than on top. After 3 – 4 monolayers deposition, RE-V NCs form a continuous layer and then grow via “layer-by-layer” modes for the remaining growth. We have used cross-sectional high-resolution High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) to study the ErSb NC formation as a result of 1 monolayer ErSb deposition on molecular beam epitaxially grown GaSb(001) surfaces. The HAADF-STEM studies clearly show the formation of ErSb NCs “within” the GaSb substrate surface consistent with the in-situ surface science studies and the embedded growth model.3,4 In this presentation, we will correlate ex-situ cross-sectional HAADF-STEM results with in-situ reflection high-energy electron diffraction, low-energy electron diffraction, x-ray photoemission spectroscopy, and scanning tunneling microscopy studies to determine the unique formation mechanism involved during the growth of ErAs and ErSb NCs in III-V semiconductors. This work was supported in part by ARO and NSF-MRSEC. This abstract is subject to government rights.
1 W. Kim, Phys. Rev. Lett. (2006).
2 M.P. Hanson, Appl. Phys. Lett. (2004).
3 B.D. Schultz, Phys. Rev. B (2006).
4 B.D. Schultz, Appl. Phys. Lett. (2006).