On the field enhanced carrier generation in MOS structures

Abstract

Using a sine voltage sweep C-V, DLTS, gettering and defect revealing techniques the thermal carrier generation in MOS (Metal - Oxide - Semiconductor) structures was investigated. The thermal generation from a field dependent becomes as field independent due to the gettering. The activation energy of generation - recombination centers, $E_{a}$, the generation lifetime, $\tau_{g}$, and Poole-Frenkel factor, $\alpha$, were determined. Dislocations with an average density of $5\times10^6 cm^{-2}$ were observed in all wafers. In the samples with field enhanced carrier generation a linear dependence between $E_{a}$ and $\alpha$ was found, where the Poole-Frenkel factor increases with the increase of the activation energy. On the other hand $E_{a}$, $\tau_{g}$ and $\alpha$ were found to be strongly affected by the gettering, thereby suggesting that they depend on the level of decoration of the dislocations with impurities.