A tunneling current density model for ultra thin HfO_2 high-k dielectric material based MOS devices

摘要

In this paper, an analytical model for evaluation of tunneling current density of ultra thin MOS devices is presented. The impacts of the promising high-k dielectric material, HfO_2 on the current density model have been carried out. In this work, improvement in the results is brought in by taking into account the barrier height lowering due to the image force effect. The considered voltage range is from 0 to ψ_1/e i.e., 0＜ V ＜ψ_1/e, where ψ_1 is the barrier height at the interface of metal and the oxide. Initially we are neglecting the image force effect for a MOS device consisting asymmetric barrier. Later, image force effect of ultra thin oxide layer has been introduced for practical potential barrier by superimposing the potential barrier on the trapezoidal barrier. Theoretical predictions are compared with the results obtained by the 2-D numerical device simulator ATLAS and published experimental results. Excellent agreements among the three are observed.