Human-Body-Model Electrostatic-Discharge and Electrical-Overstress Studies of Buried-Heterostructure Semiconductor Lasers

Optoelectronic components such as laser diodes, light-emitting diodes, and photodiodes are susceptible to electrostatic discharge (ESD) and electrical overstress (EOS). Human-body model (HBM) is the most widely adopted method for the characterization of the ESD performance. In this paper, we report a comprehensive study of the ESD and EOS characteristics of buried-heterostructure (BH) semiconductor lasers using the HBM. Threshold current, optical power, optical spectrum, and reverse-bias current are characterized during the ESD study. We show that the ESD-failure thresholds depend upon the polarity. The chip can sustain the highest ESD stress under forward bias and the lowest one under forward/reverse bias. We also show that the BH lasers exhibit two types of ESD-degradation behavior. The soft degradation is characterized by a gradual increase in the threshold current, whereas the hard degradation is identified by a sudden jump in the threshold current during the ESD voltage ramp. The ESD-degradation behavior seems to be influenced by the cavity length. The failure-analysis results show that about 27% of the ESD failure is related to facet damage. The damage regions occur at the upper laser mesa structure and form preferentially on the bond-pad side. The preferential formation of the facet damage is suggestive of current-crowding effect. We have also found that the ESD-degradation behavior is a function of the facet damage. The soft-degradation failure shows a stronger correlation with the facet damage than the hard-degradation one. Finally, we demonstrate that the ESD performance of the laser can be improved by adding a protection diode.