High External Quantum Efficiency of Electroluminescence from Photoanodized Porous Silicon

Abstract
Porous silicon (PS) light emitting diodes (LEDs) were fabricated from p+n Si wafers by photoanodization. The maximum external quantum efficiency (ηext) of electroluminescence (EL) from PS-LED up to 0.8%, which is the highest ever reported for PS-LEDs with solid state contact, was achieved under pulsed operation with 1% duty in ambient air. However, we found that PS-LED with a high ηext was accompanied by the problem of high series resistance.