Selective area wavelength tuning of InAs/GaAs quantum dots obtained by TiO2 and SiO2 layer patterning

Lee, H. S.; Rastelli, A.; Kiravittaya, S.; Atkinson, P.; Bof Bufon, C. C.; Mönch, I.; Schmidt, O. G.

doi:doi:10.1063/1.3120229

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Spin-charge-lattice coupling through resonant multimagnon excitations in multiferroic BiFeO₃

Spin-charge-lattice coupling mediated by multimagnon processes is demonstrated in multiferroic BiFeO3. Experimental evidence of two- and three-magnon excitations as well as multimagnon coupling at electronic energy scales and high temperatures are reported. Temperature dependent Raman experiments show up to five resonant enhancements of the two-magnon excitation below the Néel temperature. These are shown to be collective interactions between on-site Fe d-d electronic resonance, phonons, and mu...

In-plane anisotropy of polarized photoluminescence in M-plane (100) ZnO and MgZnO/ZnO multiple quantum wells

Highly polarized photoluminescence (PL) from M-plane ZnO layers and MgZnO/ZnO quantum wells (QWs) grown on ZnO substrates were observed. The energy difference between PL peaks of E⊥c and E∥c corresponded to that between A- and C-excitonic transitions. The polarization degree (P = 0.43) at 300 K in QWs was slightly low due to confinement-induced admixture of the Pz orbital to A-excitonic states compared with the ZnO layers (P = 0.49). Furthermore, layers with anisotropic compressive strains also...

Selective area wavelength tuning of InAs quantum dots (QDs) in GaAs matrix is achieved by patterning TiO₂ and SiO₂ layers on the sample surface followed by rapid thermal processing. After heat treatment, the QD emission under the SiO₂ capped areas shows pronounced blueshifts compared with regions capped with TiO₂/SiO₂, where interdiffusion is strongly suppressed. Finite element calculations of the strain generated by the different thermal expansion coefficients of GaAs, SiO₂, and TiO₂ at high temperature are used to interpret the results. This method may provide a simple route to achieve monolithic integration of optoelectronic devices based on QDs.

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KEYWORDS and PACS

Keywords

chemical interdiffusion, finite element analysis, gallium arsenide, heat treatment, III-V semiconductors, indium compounds, optical tuning, photoluminescence, rapid thermal processing, semiconductor quantum dots, silicon compounds, spectral line shift, thermal expansion, titanium compounds

PACS

73.21.La

Quantum dots
66.30.Pa

Diffusion in nanoscale solids
81.07.Ta

Quantum dots
66.30.Ny

Chemical interdiffusion; diffusion barriers
78.67.Hc

Quantum dots
78.55.Cr

III-V semiconductors
65.40.De

Thermal expansion; thermomechanical effects
65.80.-g

Thermal properties of small particles, nanocrystals, nanotubes, and other related systems

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http://dx.doi.org/10.1063/1.3120229

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0003-6951 (print)

1077-3118 (online)

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American Institute of Physics

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