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Abstract:
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Heterostructures of materials with dramatically different properties are exciting for a variety of devices . In particular , the epitaxial integration of metals with semiconductors is promising for low -loss tunnel junctions , embedded Ohmic contacts , high -conductivity spreading layers , as well as optical devices based on the surface plasmons at metal /semiconductor interfaces . This thesis investigates the structural , electrical , and optical properties of compound (III -V ) semiconductors employing rare -earth monopnictide (RE -V ) nanostructures . Tunnel junctions employing RE -V nanoparticles are developed to enhance current optical devices , and the epitaxial incorporation of RE -V films is discussed for embedded electrical and plasmonic devices . Leveraging the favorable band alignments of RE -V materials in GaAs and GaSb semiconductors , nanoparticle -enhanced tunnel junctions are investigated for applications of wide -bandgap tunnel junctions and lightly -doped tunnel junctions in optical devices . Through optimization of the growth space , ErAs nanoparticle -enhanced GaAs tunnel junctions exhibit conductivity similar to the best reports on the material system . Additionally , GaSb -based tunnel junctions are developed with low p -type doping that could reduce optical loss in the cladding of a 4 μm laser by ~75 % . These tunnel junctions have several advantages over competing approaches , including improved thermal stability , precise control over nanoparticle location , and incorporation of a manifold of states at the tunnel junction interface .
Investigating the integration of RE -V nanostructures into optical devices revealed important details of the RE -V growth , allowing for quantum wells to be grown within 15nm of an ErAs nanoparticle layer with minimal degradation (i .e . 95 % of the peak photoluminescence intensity ) . This investigation into the MBE growth of ErAs provides the foundation for enhancing optical devices with RE -V nanostructures . Additionally , the improved understanding of ErAs growth leads to development of a method to grow full films of RE -V embedded in III -V materials . The growth method overcomes the mismatch in rotational symmetry of RE -V and III -V materials by seeding film growth with epitaxial nanoparticles , and growing the film through a thin III -V spacer . The growth of RE -V films is promising for both embedded electrical devices as well as a potential path towards realization of plasmonic devices with epitaxially integrated metallic films . |