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A kinetic many-body electron-related model of crystallization in a-Si:H(F) in the presence and absence of metal contacts is proposed. The model expresses the parameters of the formation of crystalline nuclei in terms of atomic and electronic material characteristics. The model is based on the kinetic electron-related theory of thermally activated rate processes in solids. The model considers picosecond atomic and electronic phenomena occurring in the nanometer vicinity of strongly fluctuating Si atoms executing diffusionlike jumps over energy barriers to more ‘‘ordered’’ positions which are associated with the formation of crystalline nuclei. The influence of random picosecond fluctuational heatings (coolings) in the nanometer vicinity of hopping atoms on the nucleation (crystallization) rate is considered. The following main results are obtained. (i) The Arrhenius-like equations for the nucleation time tN linking it with the Si self-diffusion in the metal/semiconductor interface are found from the kinetic consideration of the crystallization process, and are in agreement with experimental data. (ii) The Arrhenius activation energy ΔE and the pre-exponential factor t0N of the nucleation process are calculated. They are expressed in terms of local parameters that characterize picosecond atomic and electronic processes which occur in the nanometer neighborhood of the hopping Si atoms. (iii) The ‘‘abnormally’’ large variations in the prefactor t0N (about 11 orders of magnitude) and the activation energy ΔE (a factor of 7.5) caused by metal contacts are explained. (iv) An explanation for a linear dependence between ln t0N and ΔE found experimentally in the crystallization in a-Si:H and a-Si:F is suggested. This dependence is known as the compensation effect (CEF). (v) Coefficients in the CEF equation and other kinetic parameters are calculated and expressed in terms of material characteristics, and are in good agreement with experimental data. (vi) An explanation for the large observed differences in the rate of nucleation in a-Si:H and a-Si:F is suggested. (vii) Causes for observed considerable differences in the effects of metals not forming and forming silicides on the crystallization are discussed. (viii) Si self-diffusion coefficients are calculated from the nucleation parameters in a-Si:H, a-Si:F, and in the metal/a-Si:H(F) interface for the following systems: a-Si:H/Al; a-Si:H/Pd; a-Si:F/Al; and a-Si:F/Pd.

A new kinetic many-body model for the regrowth mechanism of pure and highly doped amorphous silicon is reported. This model, which is applicable to the study of other regrowth processes, is based on the kinetic many-body theory of thermally activated rate processes in solids. It explains (a) the enhanced recrystallization rate when 8, P, and As atoms are introduced into amorphous Si, (b) the reduced recrystallization rate when amorphous Si contains 0 and C atoms, and (c) the impurity-concentration dependence of the regrowth rate.where k is Boltzmann's constant and the measured activation energy for the regrowth of pure amorphous Si (a-Si) is DE=2.3 eV. '~T his regrowth rate is enhanced by a factor of 20 to 40 when the a-Si contains high concentrations of dopant impurities (a; =0.5-1 at. % of B, P, or As). 's The ratio between the regrowth rate coefficients of pure and doped Si is exp -= 20 to 40, Kor sE' P OP (2)where P and I stand for pure and impurity-doped a-Si, respectively, and SE' AERY' -EEL & 0 is the negative difference between the activation energies in doped and pure aSi. On the other hand, the regrowth rate is reduced when 0, C, N, and noble gases are introduced into a-Si. 4 Then & Kr, SE" bE"-~E i &0 It has been suggested that the recrystallization of pure aSi occurs through nucleation folio~ed by epitaxial growth. 'The regrowth is governed and limited by a self-diffusion mechanism.%hen a-Si contains dopant impurities, it has been assumed that the impurities modify the position of the Fermi level, ' which helps the recrystallization process.However, a mechanism for the atomic rearrangement and for its modification by impurities, which changes the regrowth rate, has not yet been proposed.In this paper we propose a new kinetic many-body model which explains the recrystallization of pure a-Si and of a-Si containing high impurity concentrations. The recrystallization is considered to be a thermally activated rate process, and a new kinetic many-body theory of rate processes"' is used to calculate the rate coefficients E~and KI. The problem under consideration is too complex to be solved exactly; we will therefore confine ourselves to qualitative and semiquantitative arguments which lead to experimentally verifiable effects which are in excellent agreement with observaThe regrowth of pure and doped materials from amorphous to crystalline structures is a thermally activated process, with a rate coefficient described by the Arrhenius equation 5E' K = Koexp --kT tions. This model can be extended to the study of the recrystallization of other materials, surface segregation, particle migration, adsorption, crystal growth of mixed crystals, etc. The basic concepts of this theory and its application to diffusion and melting have been summarized in Ref. 11. This theory has been applied to various processes, such as exoelectronic emission, " transient local defects" ' and their interaction with electrons, "" electron tunneling, "'5 field-emission flicker noise, ' and the surface thermally activated rate processes....