HALL-MOBILITY MINIMUM OF TEMPERATURE-DEPENDENCE IN POLYCRYSTALLINE SILICON

Molten zone recrystallized as well as sheet grown polycrystalline sili con has shown a minimum in the temperature dependence of the Hall mobi lity. In order to explain this experimental finding a new model is pro posed, which is based on negatively charged grain boundaries for the p -type silicon material under study. This results in a potential well a t the grain boundaries instead of the more generally observed potentia l barrier. A key feature in the model is that the space charge density at the grain boundary depends on the Fermi level position and therefo re on temperature. In addition, the change in the measured Hall mobili ty before and after hydrogen passivation of the grain boundaries is di scussed. (C) 1998 American Institute of Physics.