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Interfacing various materials results in stresses and strains that typically alter the properties of either or both interfaced surfaces. In this work, we focus on enhanced light emission properties at the bandgap for silicon interfaced with silica or layers of silica and silicon nitride. This discovery is corroborated by several evidences of engineered stresses and strains at the bulk or interface...
To measure, map and control temperature, imaging of materials in a thermal furnace routinely utilizes non-contact sensors, such as pyrometers. These pyrometers require a pre-knowledge of the radiative properties of materials in the desired infrared range of wavelengths. In this study, radiative properties of some commonly used thin films of dielectric materials are investigated within the infrared...
The temperature-dependent transport properties of vanadium oxides have been studied near the Fermi energy using the Kohn–Sham band structure approach combined with Boltzmann transport equations. V2O5 exhibits significant thermoelectric properties, which can be attributed to its layered structure and stability. Highly anisotropic electrical conduction in V2O5 is clearly manifested in the calculations...
Nearly two-orders of magnitude increase in room-temperature band-to-band (1.067 eV) infrared emission from crystalline silicon, coated with erbium-doped sol–gel films, have been achieved. Phonon-assisted band-to-band emission from coated and annealed p-Si is strongest for the sample annealed at 700°C. In this paper, evidence of the origin of the emission band from the band edge recombination activities...
In Part II of this study, approaches to improve the thermoelectric figure of merit (ZT) of graphene nanosheets and nanoribbons is discussed. The presence of vacancies in graphene is found to increase the ZT of zigzag graphene nanoribbons significantly. Graphene can be a promising material with much better thermoelectric performance than conventional thermoelectrics.
Thermal conductivity of pristine and doped graphene nanosheets and nanoribbons has been studied as a function of their width and length using non-equilibrium molecular dynamics simulations. Calculations of electronic thermal conductivity are presented for these structures using density functional theory (DFT). Effects of p- and n-type doping, presence of vacancies, effect of number of layers, and...
In this comprehensive study, we have performed one-electron Kohn–Sham electronic band-structure calculations of VO2, V2O3 and V2O5 in both metallic and insulating phases, implementing a full ab initio simulation package based on Density Functional Theory, Plane Waves and Pseudopotentials (PPs). Electronic band structures are found to be influenced by crystal structure, crystal field splitting and...
Silicon (Si) continues to be the dominant semiconducting material used in photovoltaic technology for the manufacture of solar cells. Si, an indirect band gap semiconducting material, has a reflectance of about 30% in the visible range of wavelengths. Standard Si solar cells are not entirely useful in the infrared spectrum region. In order to enhance the performance of silicon solar cells, reflectance...
Enhanced band-gap emission from Czochralski silicon substrates of up to ~100 times is reported. This was achieved by processing for a stressed interface resulting from baked and annealed silica films prepared by sol–gel processes. The active dopants include but are not limited to erbium and are prepared with tetraethylorthosilicate (TEOS) while forming the active precursors using oxide and nitrate...
The radio frequency plasma synthesis of nitrogen clusters stabilized on carbon nanotube sheets has been demonstrated under various conditions. Characterization of the samples produced has been carried out using micro-Raman and attenuated total reflectance-Fourier transform infrared spectroscopy. Initial investigations of the sample morphologies and compositions have also been performed using scanning...
An overview of the applications of porous silicon (PS) thin films, as antireflection coatings (ARC) in silicon solar cells and transducers in biosensors, is presented. The reflectance spectra of PS films have been compared with other conventional ARCs (such as SiNx TiO2/MgF2 and ZnS), and optimal PS ARC with minimum reflectance has been obtained. The implementation of PS into an industrially compatible...
This year marks the 40th anniversary of the invention of the first beam-lead device by Lepselter et al. Lepselter and coworkers proposed a method of fabricating a new semiconductor device structure and its application to high-frequency silicon switching transistors and ultra-high-speed integrated circuits. Beam-lead technology, also known as air-bridge technology, has established itself for its unsurpassed...
Magnetic field-assisted assembly is an integration technique for the efficient placement of a large number of nanodevices into receptor sites etched in semiconductor wafers with or without circuitry. The diverging flux from a magnetic field source helps in attaching heterostructure nanodevices into wafers. Various approaches of magnetic field-assisted assembly using air pressure, vibration assistance,...
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