Effective mobility of polycrystalline semiconductors

Abstract

Theoretical investigations are presented to explain the behaviour of effective mobility (1'*) as a function of doping density, valid for all grain sizes, in polycrystalline silicon, by considering the dynamics of capture and release of free carriers at the grain boundary trapping sites, the finite thicknesses of the grain boundaries and the contributions of the bulk and depletion regions towards the electrical conductivity. An empirical formula is used for the value of grain boundary trapping states density (NT) as a function of grain size. Computations show that (a) 1'* has a minimum for a particular doping concentration for a given grain size D, and it shifts towards lower doping concentration with increasing D; and (b) the polycrystalline behaviour approaches the single-crystal behaviour for D ;" 3000 11m. The predicted results reasonably represent the experimentally observed variations of effective resistivity and effective mobility of polysemiconductors as a function of doping density for all grain sizes.

Conductive Polymer-Assisted Metal Oxide Hybrid Semiconductors for High-Performance Thin-Film Transistors

“…Due to the chemical interaction between InO x and PANI chain, the crystallinity of InO x semiconducting films is significantly reduced even with a trace amounts of dopant. In the case of the pristine InO x due to the existence of the grain boundary depending on the polycrystalline structure, there were trap sites deteriorating the charge transport pathway in the semiconducting film. , In comparison to this, when PANI chains are being embedded into the polycrystalline structure of InO x at an optimized ratio, the PANI chains induce that the InO x semiconducting film can effectively frustrate their crystallinity into a more amorphous phase. Thus, the PANI chains contribute to the improved electrical characteristics of InO x semiconducting films.…”

An Analytical Model of the Influence of Grain Size on the Mobility and Transfer Characteristics of Polysilicon Thin-Film Transistors (TFTs)

“…The trapping states density (N T ) is found to decrease with increasing grain size (D G ) which may be attributed to a decrease in disorder in larger grains. To incorporate this effect, an empirical relation between N T and D G which fits with the experimentally available value is given by [9]:…”