Interface contribution to the capacitance of thin-film Al-Al2O3-Al trilayer structures

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Abstract
A dual‐gun reactive ion beam sputtering technique has been used to reproducibly fabricate Al2O3 dielectrics with low electrical loss for controlled thickness ranging from approximately 10 to 360 Å. The linear dependence of the reciprocal capacitance on dielectric thickness of Al‐Al2O3‐Al trilayer structures incorporating this dielectric reveals a significant contribution from an interfacial capacitance in series with the geometric capacitance. Room‐temperature measurements of both the dc resistance and the frequency‐dependent complex impedance demonstrate that, with respect to bulk, there is an enhanced frequency‐dependent dielectric loss associated with this interfacial capacitance.