On properties of boundaries and electron conductivity in mesoscopic polycrystalline silicon films for memory devices

Abstract

We present the results of molecular dynamics modelling of the structural properties of grain boundaries (GBs) in thin polycrystalline films. The transition from crystalline boundaries with low mismatch angle to amorphous boundaries is investigated. It is shown that the structures of the GBs satisfy a thermodynamical criterion suggested by Keblinski et al (1996 77 2965). The potential energy of silicon atoms is closely related to a geometrical quantity: tetragonality of their coordination with their nearest neighbours. A crossover of the length of localization is observed. To analyse the crossover of the length of localization of the single-electron states and properties of conductance of the thin polycrystalline film at low temperature, we use a two-dimensional Anderson localization model, with the random one-site electron charging energy for a single grain (dot), random non-diagonal matrix elements and random number of connections between the neighbouring grains. The results for the crossover behaviour of the localization length of the single-electron states and characteristic properties of conductance are presented in the region of parameters where the transition from an insulator to a conductor takes place.