The Effect of Gamma Radiation Exposure on Active Silicon Photonic Device Performance Metrics

• Published in: IEEE transactions on nuclear science Vol. 66; no. 5; pp. 801 - 809
• Main Authors: Hoffman, G. B., 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.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bandwidths; Business metrics; Carrier density; Carrier mobility; Dark current; Electrooptic modulators; Exposure; Gamma rays; gamma-ray effects; Germanium; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; integrated optics; integrated optoelectronics; Ionizing radiation; Junctions; Modulation; Modulators; optical fiber communication; Optical waveguides; P-n junctions; Performance measurement; photodetectors; Photodiodes; photodiodes (PDs); Photonics; PIN photodiodes; Radiation dosage; Radiation effects; Silicon; Silicon dioxide; silicon photonics; silicon photonics (SiP); space radiation; Time constant; total ionizing dose; total ionizing dose (TID); γ Radiation
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2019.2907582

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 60 Co 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 SiO 2 -Ge interface and the gamma radiation has a minimal effect on carrier mobility.