Amorphous silicon

About: Amorphous silicon is a research topic. Over the lifetime, 26777 publications have been published within this topic receiving 423234 citations.

Near-infrared femtosecond laser-induced crystallization of amorphous silicon

Abstract: Amorphous silicon (a-Si) was crystallized by femtosecond laser annealing (FLA) using a near-infrared (λ≈800nm) ultrafast Ti:sapphire laser system. The intense ultrashort laser pulses lead to efficient nonlinear photoenergy absorption and the generation of very dense photoexcited plasma in irradiated materials, enabling nonlinear melting on transparent silicon materials. We studied the structural characteristics of recrystallized films and found that FLA assisted by spatial scanning of laser strip spot constitutes superlateral epitaxy that can crystallize a-Si films with largest grains of ∼800nm, requiring laser fluence as low as ∼45mJ∕cm2, and low laser shots. Moreover, the optimal annealing conditions are observed with a significant laser-fluence window (∼30%).

Structures and coalescence behavior of size-selected silicon nanoclusters studied by surface-plasmon-polariton enhanced raman spectroscopy

Abstract: The structures and coalescence behavior of size-selected, matrix-isolated silicon clusters have been studied using surface-plasmon-polariton ~SPP! enhanced Raman spectroscopy. The cluster ions were produced in a laser vaporization source, mass selected then deposited into a co-condensed matrix of Ar, Kr or N2 on a liquid He cooled substrate. Raman spectra from monodisperse samples of the smaller clusters studied, Si 4 ,S i 6and Si7, show sharp, well-resolved, vibrations which are in good agreement with predictions based on ab initio calculations. From these comparisons we confirm that Si 4 is a planar rhombus, and assign Si6 as a distorted octahedron and Si7 as a pentagonal bypyramid. Si5 depositions down to 5 eV did not reveal a measurable Raman spectrum under our experimental conditions. Evidence for cluster‐cluster aggregation ~or fragmentation! was observed under some conditions, even for a ‘‘magic number’’ cluster such as Si 6. The spectra of the aggregated small clusters were identical to those observed for directly deposited larger cluster ‘‘bands,’’ such as Si 25‐35. The Raman spectra of the aggregated clusters bear some similarity to those of bulk amorphous silicon. Cluster-deposited thin films were prepared by sublimating the matrix material. Even under these ‘‘soft landing’’ conditions, changes in the Raman spectrum are observed with the thin films showing even greater similarity to amorphous silicon. © 1999 American Institute of Physics.@S0021-9606~99!70521-0#

Hydrogen diffusion and electronic metastability in amorphous silicon

Abstract: Hydrogen diffusion and its role in the many electronic metastability phenomena in hydrogenated amorphous silicon (a-Si:H) is reviewed. A-Si:H contains about 10 at% hydrogen, most of which is bonded to silicon. The hydrogen diffuses at relatively low temperatures by releasing hydrogen from the Si-H bonds into interstitial sites. The reactions of hydrogen with the silicon dangling bonds and the weak bonds provide a hydrogen-mediated mechanism for electron-structural interactions, which are manifested as electronic metastability. The annealing of light-induced defects, the equilibration of defects and dopants, the stretched exponential relaxation kinetics, and the atomic structure formed during growth, are all attributed to hydrogen diffusion.

Barrier at the interface between amorphous silicon and transparent conducting oxides and its influence on solar cell performance

Abstract: We have found that a heterostructure made of a conductive transparent oxide (SnO2, ITO, or Pt:SiO2) and p‐type or n‐type or intrinsic a‐Si:H shows a substantial potential barrier at the interface. This barrier is important in order to explain the behavior of Voc versus doping of the p layer in p‐i‐n solar cells. The barrier should also be taken into account in order to explain the poor blue response of solar cells.