Non-Linear Junction Characterization
DEFENCE RESEARCH ESTABLISHMENT OTTAWA (ONTARIO)
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The phenomena of non-linear junctions formed by contacting metal surfaces was investigated and a method to characterize these junctions is described. Normally linear components, such as points of contact, can become nonlinear elements. These can occur in coupling hardware of coaxial transmission lines, in flanged joints of wave guides and in other waveguide components that are bolted together. Chemical compounds build up on metal contact surfaces exposed to the atmosphere. The compounds, oxides and sulphides for example, are semiconductive and tend to increase contact resistance. They have a non-linear current-voltage characteristic that can be used to characterize Metal-Oxide- Metal junctions by non-linear measurements. When a pure sinusoidal current flows through a component point of contact the voltage across it is distorted by any nonlinearities present. The distorted voltage can be considered the sum of a fundamental frequency voltage and a number of voltages at harmonic frequencies. The magnitude of these harmonic voltages can serve as a measure of the nonlinearity present in the contact. For convenience, the third harmonic is usually chosen since it has the largest magnitude and therefore is easiest to measure.
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