A simple approach to study time evolution of trapped electrons in metal-oxide-semiconductor devices

Abstract

A simple and effective analytical model is developed to calculate the lifetime of an electron trapped in the oxide layer of a metal-oxide-semiconductor (MOS) device using quantum analysis. A new approach applying transmission line techniques is introduced to study the time evolution of the electron wave function localized in a trap quantum well in the MOS device oxide. Treating it as a one dimensional problem, with tunneling probabilities through both oxide/metal and oxide/semiconductor interfaces, and exploiting the effective similarity with the time evolution of an electron wave packet localized in a double barrier quantum well, a model is developed to calculate the lifetime of a trapped electron under flat band conditions. It is further extended to calculate the effective lifetime of electrons trapped at various trap centers in the oxide layer under externally applied electric fields. Results thus obtained show reasonable agreement and consistency with physical concepts and experimental observations.