Electrical harmonic generation from notched narrow metal lines

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Abstract
A model for electrical harmonic generation in metal thin films has been developed based on the solution to the thermal diffusion equation using a Green’s function method and a number of simple assumptions. The validity of the model is demonstrated by measurements of the amplitude of the second and third harmonic signals using uniform aluminum lines on sapphire. By introducing damage in the form of narrow notches of prescribed size into the aluminum lines, we have been able to calibrate, and compare, the notch sensitivities of the dc resistance and the second and third harmonic signals. Predictions based on a simple approximate treatment of the notches yields good agreement with damage sensitivity of both the resistance and harmonic signals. It was found that the second and the third harmonic signals are equally sensitive to damage in the aluminum lines. Furthermore, the harmonic signals are considerably more sensitive to the presence of damage than is the dc resistance. Also, the effect of a number of distinct damage sites in a line is shown to be a linear superposition of each for both the harmonic signals and the resistance.