Degradation of the electrical characteristics of the Si–SiO2 interface induced by electron injection

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Abstract
The effects of electron injection on the electrical characteristics of the Si–SiO2 interface have been studied on metal‐oxide‐semiconductor type structures incorporating very thin oxide films (≲200 Å). Electron current across the oxide is obtained by Fowler–Nordheim tunneling in Al:SiO2:Si structures or by enhanced Fowler–Nordheim tunneling in Al:Si‐rich‐SiO2:SiO2:Si devices. The changes induced by charge injection in these structures were monitored by measuring the 1‐MHz and the quasistatic capacitance versus voltage characteristic curves. In both structures negative charge trapping in the oxide and positive charge accumulation were observed as well as generation of interface states at approximately 0.6 eV from the top of the Si valence band. However, in structures with Si‐rich‐SiO2 layers an anomalous peak in the quasistatic capacitance curves was observed to be induced by the injection of electrons. The role of the Si‐rich‐SiO2 layer in these phenomena is discussed.