Silicon photonics is a fundamental technology, which has great potential applications in optical interconnection for telecom, datacom, and high performance computers, as well as in bio-photonics. Currently considered are the photonics integrated circuits that are able to work in harsh environments such as high energy equipment and future space systems including satellites, space stations and spacecraft. The understanding of the radiation effects of the photonics devices is critical for fabricating radiation hardened photonic integrate chips and maintaining the performance of the devices and the systems. In this paper, the recent progress of the radiation effects of silicon photonic components is summarized. The effects of the high energy particles that possibly degrade the performance of the device are explained, and the response of the passive and active device under radiation are reviewed comprehensively, including waveguides, ring resonators, modulators, detectors, lasers and optical fibers and so on. For passive devices, radiation-induced effects include accelerated-oxidation of the structures, radiation-generated lattice defects, and amorphous densification or compaction in the optical materials. The effective refractive index of the passive device may change consequently, leading the working frequency to shift, the optical confinement to decrease, and the optical power to leak, which accounts for the extra loss or other performance degradation behaviors. For photodetectors and lasers, radiation-induced displacement damage will be dominant. The induced point defects localized in the silicon layer bring about deep level in the forbidden band, acting as generation-recombination centers or trap centers of tunneling effect, which will compensate for either donor or acceptor levels, degrading the response of these optoelectronic device significantly. The plasma dispersion effect is the mainstream approach to building the silicon electro-optic modulators, which will suffer ionization damage in the high energy particle environment, because the interface-trapped hole caused by ionizing radiation reduces the carrier concentration in the depletion region and even induces the pinch-off of the p-doped side of the modulator, which may result in device failure. To improve the radiation hardness of the silicon photonic device, the passivation of the surface, optimization of the waveguide shape, and the choice of appropriate thickness of the buried oxide layer are possible solutions, and more effective approaches are still to be developed.
This paper investigates total-ionizing-dose-induced body shielding effect in 130 nm T-gate partially-depleted SOI I/O nMOSFETs. As total ionizing dose increases, the body effect is useless to control the threshold voltage. A body neck pinchoff model is proposed to interpret that phenomenon. During irradiation under PG bias, high electric field is built in the buried oxide under the body neck region. Hence, more radiation-induced positive charges are trapped in the buried oxide under the body neck region. Then, the body neck region will be fully depleted. That is to say, the body neck will be pinched off as total ionizing dose increases. As a result, the body contact is shield. And the method using body voltage to control the threshold voltage does not work.
The hot carrier effect of 130-nm partially depleted SOI pMOSFETs fabricated on wafer modified by silicon ions implantation is reported in this paper. Due to the electron traps in the buried oxide, the degradation induced by hot-carrier injection is anomalous. Specifically, at low Vg stress, the positive degradation of modified pMOSFETs is faster and more serious than control devices, and huge leakage current is found after a period of stress time. Moreover, at a Vg = Vd stress, the control pMOSFETs present lightly negative degradation, while the modified pMOSFETs present enormous positive degradation. Finally, a reasonable interpretation is proposed that the deep electron traps in the buried oxide can capture hot electrons during the stress, which will cause the back channel exhausted even inversed and enhance the coupling effect between the front gate and the back gate.
A heavy-ion irradiation experiment is studied in digital storage cells with different design approaches in 130 nm CMOS bulk Si and silicon-on-insulator (SOI) technologies. The effectiveness of linear energy transfer (LET) with a tilted ion beam at the 130 nm technology node is obtained. Tests of tilted angles θ = 0°, 30° and 60° with respect to the normal direction are performed under heavy-ion Kr with certain power whose LET is about 40MeVcm2/mg at normal incidence. Error numbers in D flip-flop chains are used to determine their upset sensitivity at different incidence angles. It is indicated that the effective LETs for SOI and bulk Si are not exactly in inverse proportion to cos θ, furthermore the effective LET for SOI is more closely in inverse proportion to cos θ compared to bulk Si, which are also the well known behavior. It is interesting that, if we design the sample in the dual interlocked storage cell approach, the effective LET in bulk Si will look like inversely proportional to cos θ very well, which is also specifically explained.
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