研究目的

Understanding the origin and protocols to induce performance degradations of silicon photonics high speed photodetector represent a major issue for the qualification of the reliability of these devices.

研究成果

This work shows at first that some significant figures of merits of Ge photodetectors like dark and photonic currents can be strongly degraded during stress experiments, which could eventually lead to device failure. A model of dark and photonic currents has been presented, which can reproduce both static characteristics and degradation obtained during stress by simply decreasing the carrier lifetime τ. Extraction of the thermal activation energy of the dark current confirms the results obtained with the model and shows an increase of the SRH drift contribution in the dark current. These degradations could be due to increased surface recombination at the interface between germanium and silicon, and germanium and SiO2.

研究不足

The temporary increase of the dark current before 104 s, which have been observed on several devices, is not explained by the model of equation (6), as this function of τ only describes the stress-induced degradation, and not the variation occurring during the first hour of operation. The trends, ranges and amplitudes of the variation before 104 s seem different than the steady degradation after 104 s This phenomenon may hence have a different origin than the degradation observed after 104 s and could be due to short term reorganization of the interfaces during the first hours of the device operation.