The formation mechanisms and properties of TiSi, on Si are investigated. The particular emphasis is in relating the nucleation, morphology, and phase stability of the films. TiSi, films were prepared by deposition of Ti on atomically clean silicon substrates in ultrahigh vacuum. The silicide formation was initiated either by in situ annealing or deposition onto heated substrates. The island formation of TiSi, and surface and interface morphologies of TiSi, were examined by scanning electron microscopy and transmission electron microscopy. The TiS& formation process was monitored with in situ Auger electron spectroscopy and low-energy electron diffraction to analyze the surface concentration and the surface structures, respectively. Raman spectroscopy was used for phase identification of the TiSi,. Titanium film thicknesses from 50 to 400 A were examined. For all thicknesses studied, the C49 TiSi, phase is observed to nucleate. Immediately after low-temperature deposition, the interface morphology was smooth, but after reaction and nucleation of the C49 TiSi, phase a rough interface was observed. After highertemperature annealing the transition to the C54 TiSi, phase was observed. For TiSi, on Si ( 1 1 1 ), the interface becomes smooth and flat. The temperature of the C49-to-C54 transition was observed to vary as a function of film thickness and substrate orientation. The films exhibited island formation after high-temperature annealing. For similar Ti thicknesses and annealing temperature, different area1 coverages and island morphologies of TiSi, on Si( 100) and Si ( 111) were observed. The island morphologies are modeled and analyzed based on a liquid-liquid model, and the surface and interface energies for different TiSiz island structures are deduced from contact angle measurements. The C49 nucleation, interface morphologies, surface morphologies, and the C49-to-C54 structural phase transition are discussed in terms of surface and bulk free-energy considerations. 4269

A novel crystal growth method has been developed for the production of ingots, bricks and wafers for solar cells. Monocrystallinity is achievable over large volumes with minimal dislocation incorporation. The resulting defect types, densities and interactions are described both microscopically for wafers and macroscopically for the ingot, looking closely at the impact of the defects on minority carrier lifetime. Solar cells of 156 cm2 size have been produced ranging up to 17% in efficiency using industrial screen print processes.

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The strain patterns detected by x-ray topography in wafers bonded for silicon-on-insulator (SOI) technology were found related to the flatness nonuniformity of the original wafers. Local stresses due to the bonding process are estimated to be about 1 X 10 8 dynes/ cm 2. The stress is reduced about 100 times for the thin (0.5 µm) SOI films. Most of the wafer deformation occurs during room temperature mating of the wafers. The deformation is purely elastic even at 1200 °C. The magnitude of the stress appears insignificant for complimentary metal-oxide-semiconductor devices performance.

Electronic grade Czochralski and float zone silicon in the as grown state have a very low concentration of recombination generation centers (typically <1010 cm−3). Consequently, in integrated circuit technologies using such material, electrically active inadvertent impurities and structural defects are rarely detectable. The quest for cheap photovoltaic cells has led to the use of less pure silicon, multi‐crystalline material, and low cost processing for solar applications. Cells made in this way have significant extrinsic recombination mechanisms. In this paper we review recombination involving defects and impurities in single crystal and in multi‐crystalline solar silicon. Our main techniques for this work are recombination lifetime mapping measurements using microwave detected photoconductivity decay and variants of deep level transient spectroscopy (DLTS). In particular, we use Laplace DLTS to distinguish between isolated point defects, small precipitate complexes and decorated extended defects. We compare the behavior of some common metallic contaminants in solar silicon in relation to their effect on carrier lifetime and cell efficiency. Finally, we consider the role of hydrogen passivation in relation to transition metal contaminants, grain boundaries and dislocations. We conclude that recombination via point defects can be significant but in most multi‐crystalline material the dominant recombination path is via decorated dislocation clusters within grains with little contribution to the overall recombination from grain boundaries.