Improving the Repeatability of Ultra-High Resistance and Resistivity Measurements

High impedance insulators are an integral part of today’s high performance electronic products. The purity of the materials used to construct these insulators can make the difference between a product that works properly and one that doesn’t work at all. The accepted method of measuring high resistance is to apply a large voltage to a sample and measure the small currents stimulated through that sample. However, for high resistance samples, the levels of current that must be measured are extremely low, so testing these materials accurately and repeatably can be a challenge. Other current sources, such as piezoelectric effects or discharging capacitive elements, can obscure the stimulated current one wishes to observe in order to calculate resistance and surface and volume resistivity. This paper presents a method for selectively measuring a stimulated current in the presence of other currents that may be five to ten times the magnitude of the stimulated current.