126. self-catalyzed core-shell gaas/ganas nanowires grown on patterned si (111) by gas-source molecular beam epitaxy

Department: Electrical & Computer Engineering
Research Institute Affiliation: Graduate Program in Materials Science and Engineering
Faculty Advisor(s): Charles W. Tu

Primary Student
Name: Rui La
Email: rula@ucsd.edu
Phone: 352-871-4425
Grad Year: 2018

We report mechanistic studies on the epitaxial growth of GaAs/GaNAs core-shell nanowires (NWs) on patterned Si (111) substrate by self-catalyzed selective area growth using Gas-Source Molecular Beam Epitaxy (GSMBE). Epitaxial growth conditions were obtained using a combination of dry and time-sensitive wet etching of the SiO2 growth mask and native SiO2 layer, respectively. Micro-photoluminescence (μ-PL) measurement at 6K revealed two bands peaking at 1.45 and 1.17 eV which could be emission from GaAs core and GaNAs shell. Transmission electron microscopy showed zincblende crystal structure of GaAs and GaAs/GaNAs core-shell NWs with minimal twinning near the base of the GaAs nanowires and at the tips of the GaAs/GaNAs core/shell nanowires. This study illustrates the feasibility of the epitaxial growth of patterned GaAs with dilute nitride shells on Si substrates of potential for Si friendly intermediate band solar cells and telecom emitters.

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