Physics of Amorphous Silicon–Carbon Alloys

Luminescence and related investigations of recombination in hydrogenated amorphous silicon prepared by glow discharge and sputtering are described. Emphasis is given to a detailed discussion of the various competing radiative and non-radiative recombination mechanisms. The evidence of the luminescence data is compared to other measurements that involve recombination processes. The experiments demonstrate that the dominant luminescence is a tunnelling transition between band tail electrons and holes. Other luminescence transitions involving defects and impurities, and the role of phonon interactions in the transition are discussed. Experiments in which luminescence is used as a probe of the properties of a-Si:H and related materials are also discussed.

Luminescence and recombination in hydrogenated amorphous silicon

Structural characterization of noncrystalline solids and glasses using solid state NMR

The energy and angular distribution of ions striking the electrodes in rf discharges are of interest with respect to the application of such discharges to the processing of semiconductor materials. The ability to fabricate small (< 1 μm) semiconductor features using the plasma etching process results, in part, from the energetic and anisotropic flux of ions which strike the semiconductor surface. In this paper the energy and angular distribution of ions striking the electrodes in low‐pressure capacitively coupled rf discharges are studied using a Monte Carlo model for ion trajectories and a parametric model for the time‐dependent electric field within the sheath. Energy and angular distributions are discussed as a function of rf frequency, ion mass, and the mean‐free path between charge exchange collisions within the sheath. The ion energy distribution is found to be characterized by a scaling parameter proportional to (rf frequency × sheath thickness)2 × ion mass/(sheath voltage); small values of this parameter yield bimodal distributions, intermediate values yield distributions peaked at the maximum sheath potential, and high values yield distributions peaked at the average sheath potential. The ion energy distribution is also examined for different values of the dc and rf components of the sheath potential and for different models for the electric field within the sheaths. When the dc component of the sheath potential is small compared to the rf amplitude, a large thermal component to the ion energy distribution results. The implication of this result and that for the angular distribution of ions incident on the electrodes is discussed with respect to the isotropy of the etch obtained during plasma etching of semiconductor materials.

Distribution of ion energies incident on electrodes in capacitively coupled rf discharges

Plasma spectroscopy—Glow discharge deposition of hydrogenated amorphous silicon☆

Electrical, optical, and structural characterization of hydrogenated amorphous silicon films plasma‐deposited from mixtures of SiH4 with different inert‐gas diluents reveals substantial differences in a number of properties. A general trend of increasing defect density with atomic weight of the inert gas is observed. Of specific interest to device applications is the observation that high deposition rates can be achieved concurrently with low defect densities when helium is used as a deluent.

D. K. Bieglesen

Papers

Effects of inert gas dilution of silane on plasma‐deposited a‐Si:H films