相关论文: Local excitons in silicon induced by SiGe quantum …
The study proposes an ultra-thin back side illuminated (BSI) and top-illuminated, Ge on Si photodetector (PD), for 1 to 1.4 microns wavelength range. The Ge thickness of 350 nm allows us to achieve high-speed performance at >60 GHz, while…
Artificially ordered Ge quantum dot (QD) arrays, where confined carriers can interact via exchange coupling, may create unique functionalities such as cluster qubits and spintronic bandgap systems. Development of such arrays for quantum…
We present a detailed analysis of exciton-photon interaction in a microcavity made out of a photonic crystal slab. Here we have analyzed a disk-like quantum dot where an exciton is formed. Excitonic eigen-functions in addition to their…
The hexagonal-2H crystal phase of Ge recently emerged as a promising direct bandgap semiconductor in the mid-infrared range providing new prospects of additional optoelectronic functionalities of group-IV semiconductors (Ge and SiGe). The…
Electron-hole excitations in the surface bands of GaAs(110) are analyzed using constrained density-functional theory calculations. The results show that Frenkel-type autolocalized excitons are formed. The excitons induce a local surface…
The cubic polytype of silicon (Si) is the most commercialized semiconductor material and finds applications in numerous electronic and optoelectronic devices such as solar cells. However, recent reports on the synthesis of the hexagonal 4H…
A sequence of photoluminescence spectroscopy based methods are used to rigorously identify and study all the main spectral features (more than thirty emission lines) of site controlled InGaAs/AlGaAs quantum dots (QDs) grown along [111]B in…
We present a theoretical study of interacting electron-hole pairs located on a magnetized surface of a strong topological insulator (TI). The excitonic energy levels and the optical absorption on such surface display unique and potentially…
Silicon carbide (SiC) is the leading wide-bandgap semiconductor material, providing mature doping and device fabrication. Additionally, SiC hosts a multitude of optically active point defects (color centers) and is relevant for many…
Optimizing the photovoltaic efficiency of dye-sensitized solar cells (DSSC) based on staggered gap heterojunctions requires a detailed understanding of sub-band gap transitions in the visible from the dye directly to the substrate's…
Interlayer excitons in two dimensional semiconductor heterostructures show suppressed electron-hole overlap resulting in longer radiative lifetimes as compared to intralyer excitons. Such tightly bound interlayer excitons are relevant for…
Issues of Ge hut array formation and growth at low temperatures on the Ge/Si(001) wetting layer are discussed on the basis of explorations performed by high resolution STM and in-situ RHEED. Data of HRTEM studies of multilayer Ge/Si…
A giant built-in electric field in the growth direction makes excitons in wide GaN/(Al, Ga)N quantum wells spatially indirect even in the absence of any external bias. Significant densities of indirect excitons can accumulate in…
During a band-gap-tuned semimetal-to-semiconductor transition, Coulomb attraction between electrons and holes can cause spontaneously formed excitons near the zero-band-gap point, or the Lifshitz transition point. This has become an…
We present a first-principles study of the structural, electronic, and optical properties of hydrogenated amorphous silicon (a-Si:H). To this end, atomic configurations of a-Si:H with 72 and 576 atoms respectively are generated using…
Graphene / silicon (G/Si) heterostructures have been studied extensively in the past years for applications such as photodiodes, photodetectors and solar cells, with a growing focus on efficiency and performance. Here, a specific contact…
Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si-technology process. Here, we demonstrate strong…
The direct growth of III-V semiconductors on silicon holds tremendous potential for photonics applications. However, the inherent differences in their properties lead to defects in the epitaxial layer, including threading dislocations…
In contrast to interband excitons in undoped quantum wells, doped quantum wells do not display sharp resonances due to excitonic bound states. In these systems the effective Coulomb interaction between electrons and holes typically only…
Energy states below the bandgap of a semiconductor, such as trap states or charge transfer states in organic donor acceptor blends, can contribute to light absorption. Due to their low number density or ultrasmall absorption cross-section,…