Negative-resistance effect in Al2O3 based and nanolaminated MIS structures

It is well known the gate dielectric conduction behaviour in high-k based MIS structures is usually dominated by more than one transport mechanism. In this work, results of the electrical performance of MIS structures on n- and p-Si using Al₂O₃, HfO₂, and nanolaminated 10 nm-thick layers as gate insulators are reported. Clearly, different conduction mechanisms were observed depending on the applied bias: Fowler-Nordheim (FN) tunneling and Poole-Frenkel (PF) emission at high and moderate applied voltages, respectively, in accumulation regime and additionally, a negative-resistance region was only obtained in current-voltage (I-V) curves in inversion regime for Al₂O₃ based and nanolaminated films on pSi instead of the usual saturated curves due to exhausting of the minority carriers. A model assuming the existence of a transition interlayer between the Al electrode and Al₂O₃ with a potential well capable of capturing electrons has been developed in order to explain this atypical effect. Despite the special focus of the study is on the mechanisms of conductivity, MIS structures were also electrically characterized using other techniques besides I-V, namely, capacitance-voltage (C-V), deep level transient spectroscopy (DLTS), conductance transients (G-t), and flat-band voltages transients (V_FB-t) techniques.