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We present a general framework for simulating interfaces using an atomistic approach based on density functional theory and non-equilibrium Green's functions. The method includes all the relevant ingredients, such as doping and an accurate value of the semiconductor band gap, required to model realistic metal-semiconductor interfaces and allows for a direct comparison between theory and experiments...
Ab-initio simulations of dilute germanium carbides (Ge:C) using hybrid functionals predict a direct bandgap with <1%C. Growth of dilute Ge:C shows reduced direct gap consistent with the model, with no structural defects detected. Ge:C may enable lasers and compact modulators on Si.
The electronic band structure, and in particular the band gap directness, of binary and ternary SiGeSn alloys are first reviewed, and different aspects of their optoelectronic and microelectronic applications discussed, and the computational analysis is then extended to the dilute carbon-containing alloys.
In 1991, Soref and Perry presented a concept paper on the properties of a hypothetical ternary Ge1−x−ySixSny alloy for silicon-compatible optoelectronic applications.1 The material was finally synthesized at Arizona State University in 2003,2 opening up a new field of research that is rapidly approaching its first one-thousand publications. A very recent review article by Wirths, Buca, and Mantl provides...
Ge is an indirect band gap material. The band structure of Ge is a strong function of strain and alloy composition, and a transition from an indirect to a direct band gap has been observed for y∼6–10% for relaxed Ge1_ySny indicating the possibility of widespread applications of Ge-based photonic devices. The pseudomorphic nature of the Ge-based alloy layer on a substrate is important to keep dislocation...
Light emission from Si, would allow integration of electronic and optical functionality in the main electronics platform technology, but this has been impossible due to the indirect band gap of Si. In this talk I will discuss 2 different approaches, using unique properties of nanowires, to realize light emission from Si-based compounds.
Serving as the electrical to optical converter, the on-chip light source is the key component for monolithically integrated Group IV photonics. Here, we compare a variety of concepts for light generation on a Si chip, realized by Ge and GeSn heterostructures and quantum wells.
Phoxonic crystals are periodic nanostructures that are simultaneously photonic and phononic crystals. Phoxonic cavities can trap visible or near infrared light and Gigahertz phonons in the same tiny volume, while phoxonic waveguides can confine their propagation to a tiny solid core, in both cases possibly promoting their interaction. This paper reviews various phoxonic nanostructures that have been...
The 1.5 to 5.0 μm wavelength region is a “new band” for sensing, communications, night vision and other significant applications enabled by emerging SiGeSn integrated-photonics technology. This paper gives an overview of potential mid-infrared applications and device capabilities. After R&D, it is likely that all photonic components including on-chip laser diodes, photodetectors, electro-modulators...
We present a fabrication method for a photonic crystal membrane consisting of Er2O3/Si, and investigate the induced photonic band-gap effect. We obtain a fine photonic crystal structure by selective area growth of Er2O3 on a pre-patterned Si(111) membrane by the molecular beam epitaxy method, and the fabricated Er2O3/Si photonic crystals show the suppression of the radiative transition as a result...
This paper describes the effects of the nonparabolic band structure on the intrinsic carrier concentration in In0.53Ga0.47As. In order to investigate the effects of the nonparabolic band structure on the intrinsic carrier concentration, we calculated the temperature dependence of the relative error of the intrinsic carrier concentration given by the nonparabolic and parabolic band structure of the...
Dynamically tunable characteristics of a heterojunction between two semiconducting materials offers the potential for building reconfigurable devices that can enable novel functionalities in electronic systems [1-3]. In this work, we study a novel junction between black phosphorus (BP) and tin selenide (SnSe), both with puckered orthorhombic crystal lattices. Due to the narrow bandgap of BP ∼0.3 eV...
In this paper we investigate the density of states of hexagonal silicon nanotubes. Next, we continue with the investigation of the effects two types of mechanical deformations, namely uniaxial and torsional strains on the DOS of Single Walled Silicon Nanotubes (SWSiNTs). We use tight binding model to perform DOS calculations and work out the appropriate results. It is shown that the application uniaxial...
Power generation from solar photovoltaics has been increasing since the last decades. Currently, ground-mounted solar-PV, solar rooftop-PV, Building integrated-PV, and Roof-Jack mounting system are the available methods in photovoltaics for deployment of solar energy. The performance of a solar PV system has depended mainly on conversion efficiency which depends on the material used for construction,...
Gallium phosphide nanowires (GaP-NWs) were synthesized via oxide assisted growth mechanism in a chemical vapor deposition (CVD) and their optoelectronic properties were studied. The diameters of nanowires were in the range of 20–80 nm and lengths extended up to tens of micrometers. Raman spectra studies of GaP-NWs reveal broad and intense peaks at 364 and 398 cm−1 confirmed from transverse optic (TO)...
Attention has been paid to power electronics to make energy-saving society. Though the wide bandgap semiconductors are expected to realize efficient power converters by replacing Si ones, it will be beneficial to look back their evolution paths. Si power devices have been changing their structures to adapt to the wide range of requirements such as, blocking-voltage, handling-current, and switching-speed...
All-optical logic AND gate is realized by incorporating an elliptical structure at the Y-junction of two-dimensional photonic crystal waveguides. Principle of operation of the device is based on linear optics and, hence, the device consumes very low power while having very fast response time. The proposed device works in the 1550 nm wavelength band. Additionally, the simplicity of the device structure...
We have investigated the effects of alloy composition (y) on gain of a Ge1−ySny heterostructure avalanche photodiodes (APDs). The band-offsets become a function of alloy composition and affect the carrier confinement at heterointerfaces. The photocurrent is computed using the composition dependent parameters and, hence, the effect of alloy composition on gain of the APDs have been investigated.
This paper reviews the three main thin film solar cell technologies: amorphous silicon (α-Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). The evolution of these three technologies is discussed in comparison to commercial applications, reliability, and market share. While the α-Si cell is almost extinct in terrestrial applications, CIGS and CdTe are comparable to multicrystalline...
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