Publications

The effect of gamma radiation exposure on active silicon photonic device performance metrics

Hoffman, Galen H.; Gehl, M.; Martinez, N.J.; Trotter, D.C.; Starbuck, A.L.; Pomerene, A.; Dallo, C.M.; Hood, D.; Dodd, P.E.; Swanson, S.E.; Long, C.M.; DeRose, C.T.; Lentine, A.L.

In this paper, we test Si vertical-junction disk modulators and waveguide-integrated Ge p-i-n photodiodes (PDs) to see how the key performance metrics are affected by 60Co gamma radiation (total ionizing dose), a common proxy for simulating a mix of high-energy ion particle flux. It is found that reverse bias dark current increases significantly for both devices after 1-Mrad(Si) exposure. As the bandwidth of the Si disk modulator decreases by 6.5% after 1-Mrad(Si) dose, the bandwidth of the Ge p-i-n PD appears to be unaffected. The increased sensitivity of the Si disk modulator bandwidth to gamma radiation is hypothesized to be caused by a decrease in the carrier concentration of the junction with a resulting increase in the p-n junction RC time constant. The Ge p-i-n PD is relatively insensitive to the surface effects, because the absorption happens away from the SiO2-Ge interface and the gamma radiation has a minimal effect on carrier mobility.