Using charge modulated electroabsorption spectroscopy (CMEAS), for the first time, the energy level alignment of a polymer:fullerene bulk heterojunction photovoltaic cell is directly measured. The charge-transfer excitons generated by the sub-bandgap optical pumping are coupled with the modulating electric field and introduce subtle changes in optical absorption in the sub-bandgap region. This ...

Amorphous semiconductors are materials with a brilliant prospect for a wide range of optical applications like solar cells, optical sensors, optical devices, and memories. The purpose of the present research was to study the semiconducting optical properties of SiO2-Al2O3-CaF2 and SiO2-Al2O3-BaF2 oxyfluoride...

The usefulness of graphene for electronics has been limited because it does not have an energy bandgap. Although graphene nanoribbons have non-zero bandgaps, lithographic fabrication methods introduce defects that decouple the bandgap from electronic properties, compromising performance. Here we report direct measurements of a large intrinsic energy bandgap of approximately 50 meV in nanoribbon...

the aluminum oxide materials are widely used in ceramics, refractories and abrasives due to their hardness, chemical inertness, high melting point, non-volatility and resistance to oxidation and corrosion. the paper describes work done on synthesis of α-alumina by using the simple, non-expensive solution combustion method using glycine as fuel.aluminum oxide (al2o3) nanoparticles were synthesiz...

It is well known that the excess noise factor of an avalanche photodiode (APD), which is a measure of its gain fluctuation, can be reduced by decreasing the thickness of the avalanche multiplication region. This noise reduction is attributable to the increased importance of the dead-space effect in thin layers, which prevents a carrier from impact ionizing before it travels a sufficient distanc...

The concept of 'bandgap mapping' was proposed originally to map the inhomogeneity of band energy in III-V semiconductors with a spatial resolution of a few nanometres in a scanning transmission electron microscope with the focus beam mode. In this paper, several techniques were developed to demonstrate the possibility to map the distribution of bandgap energies for GaN/AlN quantum-well structur...

We present a simple picture to understand the bandgap variation of any chiral carbon nanotubes with tensile and torsional strains. Using this picture, we are able to predict a simple dependence of d(Bandgap)/d(strain) on the value of (Nx −Ny) mod 3, for semiconducting tubes. We also predict a novel change in sign of d(Bandgap)/d(strain) as a function of tensile strain arising from a change in t...

The layered transition metal dichalcogenides have attracted considerable interest for their unique electronic and optical properties. While the monolayer MoS2 exhibits a direct bandgap, the multilayer MoS2 is an indirect bandgap semiconductor and generally optically inactive. Here we report electric-field-induced strong electroluminescence in multilayer MoS2. We show that GaN-Al2O3-MoS2 and GaN...