Crystal phase engineering of self-catalyzed GaAs nanowires using a RHEED diagram
Résumé
It is well known that the crystalline structure of the III-V nanowires (NWs) is mainly controlled by the wetting contact angle of the catalyst droplet which can be tuned by the III and V flux. In this work we present a method to control the wurtzite (WZ) or zinc-blende (ZB) structure in self-catalyzed GaAs NWs grown by molecular beam epitaxy, usingin situreflection high energy electron diffraction (RHEED) diagram analysis. Since the diffraction patterns of the ZB and WZ structures differ according to the azimuth [11̄0], it is possible to follow the evolution of the intensity of specific ZB and WZ diffraction spots during NW growth as a function of the growth parameters such as the Ga flux. By analyzing the evolution of the WZ and ZB spot intensities during NW growth with specific changes of the Ga flux, it is then possible to control the crystal structure of the NWs. ZB GaAs NWs with a controlled WZ segment have thus been realized. Using a semi-empirical model for the NW growth and ourin situRHEED measurements, the critical wetting angle of the Ga catalyst droplet for the structural transition is deduced. © The Royal Society of Chemistry 2020.
Mots clés
Spot intensities
Structural transitions
Wetting contact angles
Crystal structure
Catalysis
Catalysts
Chromium compounds
Contact angle
Drops
Gallium
Gallium arsenide
III-V semiconductors
Molecular beam epitaxy
Nanowires
Semiconducting gallium
Wetting
Zinc sulfide
Crystalline structure
Diagram analysis
Diffraction spots
Growth parameters
Semi-empirical modeling
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