Leakage current in InGaAsP avalanche photodiodes

The increased leakage current in InGaAsP APD’s near breakdown is found to be a rather uniform bulk property, not associated with conventional microplasmas, dislocations, or surface effects. Surface effects were eliminated by the fabrication of guard ring APD’s, but the increased leakage current persisted. Surface effects were further ruled out by a statistical study of the leakage current in a large sample of APD’s. The study shows conclusively that the leakage current is proportional to diode area, not perimeter.