EFFECT OF STRAIN RELAXATION ON FORWARD BIAS DARK CURRENTS IN GAAS INGAAS MULTIQUANTUM-WELL P-I-N-DIODES/

The effect of the dislocation line density produced by the relaxation of strain in GaAs/InxGa1-xAs multiquantum wells where x=0.155-0.23 has been studied. There is a strong correlation between the dark line den sity, observed by cathodoluminescence, before processing of the wafers into photodiode devices, and the subsequent low forward bias (<1.5 V) dark current densities of the devices. A comparison is made of the co rrelation between the reverse bias current density and dark line densi ty and it is found that, in this range of strain, the forward bias cur rent density varies more. Two growth methods, molecular beam epitaxy a nd metal organic vapor phase epitaxy, have been used to produce the wa fers and no difference between the growth methods has been found in da rk line or current density variations with strain. (C) 1996 American I nstitute of Physics.