AbstractSnxGe1−x alloys are grown coherent on Ge(001) substrates by conventional molecular beam epitaxy. The lattice mismatch between SnxGe1−x and Ge produces a biaxial compression of the alloy in the plane of the substrate and a uniaxial elongation in the growth direction. The change of Eg resulting from the biaxial compression is modeled with deformation potential theory for coherent SnxGe1−x on Ge(001) and coherent SnxGe1−x on Ge(111). For SnxGe1−x on Ge(001), the decrease in the energy band gap due to strain is small, 16 meV for x = 0.10, and Γ7 and L6 shift uniformly. In the case of SnxGe1−x on Ge(111), Γ7 and L6 do not shift uniformly; a large uniaxial splitting occurs at L6, 200 meV for x = 0.10. Another interesting result of a uniaxial strain along [111] is the absence of a direct to indirect energy band gap transition for x < 0.30. Fourier transform infrared spectroscopy transmission measurements of coherent SnxGe1−x on Ge(001) confirm the strain-induced change in the energy band gap is a small effect.
The correlation between the energy band-gap of AlxGa1-xN epitaxial thin films and lattice strain was investigated using both High Resolution X-ray Diffraction (HRXRD) and Spectroscopic Ellipsometry (SE). The Al fraction, lattice relaxation, and elastic lattice strain were determined for all AlxGa1-xN epilayers, and the energy gap as well. Given the type of intermediate layer, a correlation trend was found between energy band-gap bowing parameter and lattice mismatch, the higher the lattice mismatch is, the smaller the bowing parameter (b) will be.
We investigate why normal electrons in superconductors have no resistance. Under the same conditions, the band gap is reduced to zero as well, but normal electrons at superconducting states are condensed into this virtual energy band gap.
The CdS nanoparticles of different sizes are synthesized by a simple chemical method. Here, CdS nanoparticles are grown through the reaction of solution of different concentration of CdCl2 with H2S. X-ray diffraction pattern confirms nano nature of CdS and has been used to determine the size of particle. Optical absorption spectroscopy is used to measure the energy band gap of these nanomaterials by using Tauc relation. Energy band gap ranging between 3.12 eV to 2.47 eV have been obtained for the samples containing the nanoparticles in the range of 2.3 to 6.0 nm size. A correlation between the band gap and size of the nanoparticles is also established.
No Resistive Normal Electrons in Beginning Superconducting States