Complex tetrahedral structures form good models for amorphous Group IV and HI-V semiconductors. With a view of working towards examining non-crystalline materials, the structural, electronic and vibrational properties of complex tetrahedrally bonded semiconductors are investigated by various molecular dynamics techniques. First principles quantum mechanical molecular dynamics calculations are p...

When a sufficient high dose of energetic ions is implanted into a silicon crystal, irradiated zones of the crystal are transformed to an amorphous state. The thickness and spatial location of the amorphous layers determine the type of the extended defects and the number of point defects remaining in the silicon crystal after a recrystallization step. I t is believed that the lateral diffusion o...

We are familiar with large highly-ordered single crystals, such as those used in the semiconductor industry. There the crystalline ordering in the silicon crystals extends for billions and more lattice spacings. As a result, X-ray diffraction (XRD) patterns of these crystals have sharp Bragg peaks. We are also familiar with liquids, where the molecules have a local structure that is very differ...

Computational simulations are a new branch of science where one can perform computational experiments by simulating a model system. The model contains an approximation of a real system with simplified physical laws and reduced size in order to make it computationally tractable. Many physical systems cannot be analytically solved and also experimentally not everything can be measured. Computatio...

For wafer based silicon solar cells, the combination of amorphous/crystalline silicon (a-Si:H/c-Si) heterojunction emitters (SHJ) [1] and back-contacted back-junction solar cell concepts (BCBJ) [2] offer a very high efficiency potential of around 24%. Stangl et al. proposed a relatively simple and therefore attractive cell concept comprising a two level metallization isolated by an insulation l...

“Silica,” is a term which refers broadly to the mineral compound silicon dioxide (SiO2). Silica can be crystalline or amorphous. Crystalline silica is significantly more hazardous to employees than amorphous silica. In addition to causing the disabling and irreversible lung disease known as silicosis, crystalline silica has been classified as a human carcinogen by the International Agency for R...

During the last two decades, the Institute of Microtechnology (IMT) has contributed in two important fields to future thin-film silicon solar cell processing and design: (1) In 1987, IMT introduced the so-called ‘‘very high frequency glow discharge (VHF-GD)’’ technique, a method that leads to a considerable enhancement in the deposition rate of amorphous and microcrystalline silicon layers. As ...

We report on the surprisingly strong, broadband emission of coherent terahertz pulses from ultrathin layers of semiconductors such as amorphous silicon, germanium and polycrystalline cuprous oxide deposited on gold, upon illumination with femtosecond laser pulses. The strength of the emission is surprising because the materials are considered to be bad (amorphous silicon and polycrystalline cup...