Errors in Low Current Measurements (3)

One of the most common causes of error when measuring low currents (<1nA) is offset current, which can come from the test setup or the measuring instrument.

Potential Cause: Detector Dark Current

Photomultiplier tubes usually have a small current flowing even when they are not illuminated.

Remedies

This current can be cancelled out from the measurement by using the built-in zero suppression feature of the picoammeter or electrometer.