OBSERVATION AND STUDY ON THE DARK DEFECTS IN InGaAsP/InP DOUBLE-HETEROSTRUCTURE LEDs

The defects in lnGaAsP/InP DH LEDs are observed with an infrared line scanner.The darkstructure appears before aging and it exists mainly in the form of dark spot defect.The effect of the variety andconcentration of the doping for p-InP confining layers on the dark defects is studied.The results show that thepercentage of devices with dark defects is much lower for Mg or In-Zn doped devices than for Zn dopeddevices.It is believed that Zn is one of the important origin for the formation of dark defects.The growth rateof dark defects is studied both at room temperature and at 70—85℃.The results show that after agin for15000 h at room temperature there are no dark defects newly appeared.But after aging for 2000 h at 70—85℃some devices show newly formed dark structure with very slow growth rate.