Anomalous CV curves of Al/SRO/Si structure after electrical stress

Abstract

The electronic transport property of silicon-rich oxide (SRO) films under electrical stress was studied in Al/SRO/Si structures using capacitance versus voltage ( C– V) and current versus voltage ( I– V) measurements. The measured C– V curves show an unexpected vertical shift either upward or downward. Analysis of the data shows that these upward and downward shifts can be almost totally attributed to a sudden change of the capacitance of the SRO layer. I– V measurements also present some abrupt jumps in current. A simple model was proposed to explain the experimental results taking into account the change of the transport properties of the SRO layer. It is proposed that under electrical stress the SRO film can be switched between two states: low resistive and high resistive states. These conductive states are produced by the creation and, or annihilation of neutral traps, or defects, in the SRO layer. If defects are created, they will “connect” adjacent excess Si dots already existing in the material, then percolation paths would be formed and electrons could move through these paths resulting in a low resistive state. On the other hand, if the defects are annihilated by electrical stress, the percolation paths would be eliminated and the SRO layer turns to a high resistive state. Then, the switching between the on and off states of the SRO films under electrical stress would produce the anomalous shifts observed in the measured C– V and I– V curves.