Electroluminescence based determination of the space charge limited field

Determination of the space charge limited field is compromised by photon detection sensitivity. As a result, the experimental determined field is affected by the test frequency and by the photomultiplier dark count. The electroluminescence inception field determined with semicon needle is in good agreement with the space charge limited field measured using a guarded needle electrode, while metal needles with tip radii smaller than 5 mum lead to much greater predicted space charge limited field due to the much smaller light emitting volume. This electrode size effect is explained, and a correction method is proposed which results in a more accurate determination of the space charge limited field from electroluminescence measurements.