Intergranular barrier height fluctuations in polycrystalline semiconductors

C. BUONO; F. SCHIPANI; M. A. PONCE; C. M. ALDAO

Physica Status Solidi C

Wiley

Lugar: Weinheim; Año: 2017

1610-1642

The punctual character and random nature of the impuritypositions in depletion regions lead to inhomogeneities that cansignificantly affect the potential intergranular barriers atpolycrystalline semiconductors and, in general, of potentialbarriers at any semiconductor interface. This would reflect inArrhenius plots for the electrical conductivity that becomecurved due to fluctuations of the intergranular barrier heights.Experimental results for polycrystalline tin oxide can be fittedassuming thermionic emission conduction at grain boundarieswith a Gaussian distribution of barrier height fluctuations.However, resorting to a computational numerical model, wefound that spatial fluctuations in barrier heights due to thediscreteness of the donors and their statistical distribution atthe depletion region differ from a Gaussian distribution. Thetype of obtained fluctuations, considering thermionic emissionconduction, cannot explain the Arrhenius plots for theelectrical conductivity found experimentally, especially atlow temperature. Conversely, the tunneling contribution toconduction, without resorting to fluctuations, presents theobserved trends.