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AQP Seminar: Inelastic electronic light scattering and nanophotonic engineering in semiconductors

Aalto Quantum Physics Seminar (Nanotalo). Speaker: Prof. Bakhysh Bairamov (Ioffe Institute, Russia).

Strong-light matter interactions at the nanometer scale are increasingly important for modern nanophotonic and emerging optical quantum technologies. Strategy of interdisciplinary materials research of fundamental problems in nanoscale many-body light-matter interactions by the high spectral-resolution inelastic electronic light scattering spectroscopy in an extensive range of the chemical types and the carrier density from 10^11 to 10^18 cm-3 of the doping and background impurities in a wide bandgap semiconductors having technological relevance will be addressed. The experimental spectra observed together with the lattice excitations of the phonons demonstrate significant role of the influence of the electron– LO(Γ)-phonon interactions together with manifestation of the pure electronic excitations between the discrete quantized hydrogen atom-like [1s(T2) → 2p±]-, and [1s 3/2(Γ8) → 2s 3/2(Γ8)] electronic transitions. Characterizations of strain, compositional fluctuation, defects, chemical type and concentrations of impurities, mobility and concentration of free carriers, net acceptors (donor) and etc., were performed. New physical phenomena for advancing in an all-optical non-destructive and ultra-sensitive characterization techniques of semiconductor materials and nanostructures useful for simultaneous determination their crystalline and electron transport properties for optoelectronic device structures will be presented. Unique properties of interaction between light and matter can be controlled more efficiently by structuring quantum-size  materials at a length scale shorter than the wavelength of interest. The crystalline semiconductor nc-Si/SiO2 quantum dots, due to their unique physical and chemical properties, i.e., high quantum yield and possible wavelength tuning in a wide visible spectral range, are especially attractive for nanophotonic as nanosensors. The color center in crystals like nitrogen‐vacancy (NV) center in diamond has emerged also as a very versatile solid-state system for quantum information technology. The main characteristics that make it exclusive are its paramagnetic ground state, intense luminescence, extremely long spin coherence times, coupling to nearby nuclear spins. In addition to these quantum photonic applications, NV centers in diamond have been studied also as biosensors for cellular and neural activities. New physical phenomena for advancing in an all-optical non-destructive and ultra-sensitive characterization techniques of semiconductor materials and nanostructures useful for simultaneous determination their crystalline and electron transport properties for optoelectronic device structures will be presented. The results obtained provide key insights for design and optimization of device micro- and nanostructures.

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