Alexandria Digital Research Library

Semimetallic Nanorods Embedded in High-Index Semiconductors

Buehl, Trevor
Degree Grantor:
University of California, Santa Barbara.Materials
Degree Supervisor:
GossardPalmstrøm ArthurChristopher CJ
Place of Publication:
[Santa Barbara, Calif.]
University of California, Santa Barbara
Creation Date:
Issued Date:
Materials Science
Molecular Beam Epitaxy

The first reported work on nanowire growth occurred decades ago and has now been successfully reported for a wide range of both metallic and semiconducting materials. However, the vast majority of these growths produced free-standing structures. This dissertation investigates the novel growth and resulting properties of embedded RE-V semimetallic nanorods in III-V semiconductors grown by molecular beam epitaxy. Semimetal/semiconductor composite materials of ErAs and ErSb nanorods were grown by codeposition with GaAs and GaSb on high-index GaAs and GaSb substrates. Their structural, optical, and electrical properties were found to be dependent on the resulting microstructure and the growth conditions used.

An investigation of the microstructure of each growth was performed using both cross-sectional and plan-view transmission electron microscopy and scanning transmission electron microscopy in order to determine the size, shape, structure, and orientation of the embedded nanostructures. The size, shape, and periodicity of these structures were found to be dependent on the growth temperature and, to a lesser degree, on the RE concentration used. The orientation of the nanorods was found to be dependent on the orientation of the underlying substrate. Additional investigation into the morphology of codeposited TbAs and ErAs nanoparticles in InGaAs was also performed.

Optical absorption spectroscopy indicated a large, polarization-dependent resonant absorption peak in these nanostructures that was attributed to plasmon oscillations similar to those observed in metallic nanostructures. These peaks were found to be dependent on the surrounding matrix material as well as the size and shape of the nanostructures, consistent with theory. The plasmon absorption peak hinted at the semimetallic electronic structure of the underlying nanostructures, which was confirmed using scanning tunneling spectroscopy.

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