Optical Properties of Novel Semiconductor Nanostructures

Dear Colleagues,

For nearly 50 years, the effects of reduced dimensions on the optical properties of semiconductor crystals have been the focus of intense experimental and theoretical research. Beginning with impressive results from optical studies of quantum wells and superlattices in the 1970s, the effects of the quantum confinement of electrons and holes on the light emission and absorption of systems have been demonstrated for quantum dots, in self-assembled in epitaxially-grown heterostructures as well as nanocrystals synthesized in colloidal solutions. These structures have yielded a variety of applications, ranging from lasers to color displays to luminescent markers of biomolecules.

The beginning of this century brought graphene with its unique optical properties, partially arising from its intrinsic two-dimensional (2D) nature. Perhaps the most interesting (and less-explored so far) spectral ranges in terahertz (THz) and mid-IR, where plasmon-polaritons are supported in graphene, represent an intriguing subject of fundamental research with many promising applications. The graphene boom also gave rise to intense studies of other layered materials, including the family of transition metal dichalcogenides. These materials include semiconductors with band gaps in the visible range and extraordinary electronic properties, such as large exciton binding energy, well-defined Berry curvature, and strong spin-valley locking effects. Colloidal chemistry methods have also brought about novel nanoplatelet semiconductor structures, with 2D character and well-controlled photoluminescent properties.

At the same time, a considerable number of research groups around the world continue efforts to combine photonic structures with silicon electronics. Several important results have been obtained in recent years, including light emission from reduced-dimension silicon materials and silicon-compatible group IV semiconductor alloys such as Ge-Sn. Many interesting properties have also been shown in hybrid materials combining conventional or 2D semiconductors with organic emitters (dye molecules) or inorganic nanoparticles, with enhanced light absorption in specific spectral regions or optical sensing of bio- and gas molecules.

A fascinating new area of unravelling topological effects on the optical response of materials is also arising, with prominent dichroism, polarization memory, as well as interesting magneto-optical response in topological insulators and other Dirac materials. This area has recently focused on the identification and control of single-photon emitters via nanostructured substrates for a variety of 2D materials.

This Special Issue aims to gather original research articles and review papers describing experimental and theoretical results concerning the optical properties of materials where quantum confinement or reduced dimensionality play a key role. It is open to contributions covering a broad spectral range from THz to ultraviolet, investigating fundamental aspects of light–matter interactions or targeting specific applications.

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• colloidal quantum dots and core/shell structures
• nanowires
• nanoplatelets
• silicon nanostructures for optoelectronics
• Group IV materials for optoelectronics
• strain and optical response
• semiconductor 2D materials
• graphene
• nanoplasmonics
• low gap materials
• hybrid nanomaterials
• quantum and single-photon emitters
• semiconductor microcavities
• polaritons
• hyperbolic materials
• non-linear optical properties
• Van der Waals heterostructures
• topological insulators