Effects of High Fluence Particle Irradiation on Germanium-on-Silicon Photodiodes

Waveguide-Integrated germanium-on-silicon (Ge-on-Si) photodiodes (PDs) are integral components in silicon photonics (SiPh) and understanding their radiation tolerance is important for applications that intend to use SiPh in harsh radiation environments. Here we report the results of high fluence particle irradiation tests on Ge-on-Si PDs. The PD samples are irradiated using neutrons and protons, with fluences reaching up to $\mathrm {3 \times 10^{16}~n / \text {cm} ^{2} }$ (23 MeV) and $\mathrm {4.1 \times 10^{16}~p / \text {cm} ^{2} }$ (24 GeV), respectively. Throughout the neutron irradiation, changes in PD responsivity and dark current are monitored, while the capacitance and current-voltage-characteristics are measured during the proton irradiation test. The results reveal only minimal losses in responsivity, along with moderate increases in dark current and capacitance. These observed changes could impose limitations on applications that demand high bandwidth in extreme radiation environment. However, it is worth noting that for example high-energy physics experiments, which represent some of the most extreme radiation environments, do not necessarily require exceptionally high receiver bandwidths. Consequently, our findings demonstrate excellent radiation tolerance that fulfills the requirements of next-generation high-energy physics experiments.Waveguide-Integrated Germanium-on-Silicon (Ge-on-Si) photodiodes are integral components in silicon photonics and understanding their radiation tolerance is important for applications that intend to use silicon photonics in harsh radiation environments. Here we report the results of high fluence particle irradiation tests on Ge-on-Si photodiodes. The photodiode samples are irradiated using neutrons and protons, with fluences reaching up to 3 × 10 16 n/cm 2 (23 MeV) and 4.1 × 10 16 p/cm 2 (24 GeV), respectively. Throughout the neutron irradiation, changes in photodiode responsivity and dark current are monitored, while the capacitance and current-voltage characteristics are measured during the proton irradiation test. The results reveal only minimal losses in responsivity, along with moderate increases in dark current and capacitance. These observed changes could impose limitations on applications that demand high bandwidth in extreme radiation environment. However, it is worth noting that for example high-energy physics experiments, which represent some of the most extreme radiation environments, do not necessarily require exceptionally high receiver bandwidths. Consequently, our findings demonstrate excellent radiation tolerance that fulfills the requirements of next-generation high-energy physics experiments

System Development of Radiation-Tolerant Silicon Photonics Transceivers for High Energy Physics Applications

Silicon photonics enables the manufacturing of high-speed, low-power, integrated optical circuits with compact footprints, and recent studies have also shown it to have a high tolerance to radiation. The technology has, therefore, been identified as an excellent candidate for the development of the next generation of radiation-tolerant optical links for high-energy physics (HEP) experiments at CERN. This article presents the results of the characterization and modeling of building block devices and circuits for custom radiation-tolerant transceivers based on silicon photonics. We demonstrate a four-channel wavelength division multiplexing (WDM) transmitter (Tx) based on microring modulators (RMs) operating at 25 Gb/s per lane, and a polarization-insensitive receiver (Rx) based on germanium photodiodes (PD). Solutions for the thermal tuning of the RMs and on- chip active polarization control are also reported