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The related recovery mymargin mymargin effect of hydrogen on AlGaN/gallium nitride (GaN) high-electron-mobility transistors (HEMTs) irradiated by high-fluence protons was investigated in this article. The results show that under the same temperature and time conditions, the recovery effect induced by thermal hydrogen annealing is better than that of ordinary thermal annealing. Compared with the ordinary thermal annealing, the high-fluence proton-irradiated device experienced a 65-mA additional increase in saturation current at the gate-to-source voltage ( $V_{\mathrm {gs}}$ ) of 0 V, a 0.074-V additional negative shift of the threshold voltage, a more significant increase in reverse gate leakage current and better gate lag after the hydrogen treatment. The defect densities are extracted by the low-frequency noise method. It shows that the trap density decreases from $8.32\times 10^{17}$ to $6.84\times 10^{\mathrm {17 {}}}$ cm $^{-3}\cdot $ eV $^{-1}$ after ordinary thermal annealing and then decreases from $6.84\times 10^{17}$ to $3.85\times 10^{17}$ cm $^{-3}\cdot $ eV $^{-1}$ after hydrogen treatment of an irradiated AlGaN/GaN HEMT. The mechanism for the decrease of trap density after the hydrogen treatment could be attributed to the H-passivated defects in the structures of AlGaN/GaN HEMTs.

The total ionization dose (TID) effect and negative bias temperature instability (NBTI) effect of 130-nm partially-depleted silicon-on-insulator (PDSOI) MOSFETs fabricated on hardened wafers with silicon ion implantation and unhardened wafers are investigated. A TID-hardened PDSOI MOSFET up to 1 Mrad(Si) is obtained by Si+ implantation in buried oxide (BOX). The hardening benefits from the electron traps in the BOX introduced by Si+ implantation. Although the radiation hardening process has a rare impact on nominal electrical characteristics of the device before irradiation, it will affect the NBTI reliability, which is manifested as the decrease in the NBTI lifetime for the radiation-hardened devices. The energy distribution of positive charges built up during NBTI stress is obtained. It proves that more damage-related traps exist near the gate oxide/silicon interface for the radiation-hardened device, which accelerates the threshold voltage shift during the NBTI stress. This conclusion is also verified by the low-frequency noise characteristics.

The degradation mechanisms for pMOSFETs from a 130 nm partially-depleted silicon on insulator (PDSOI) technology under the combined effects of total ionizing dose (TID) and negative bias temperature instability (NBTI) are investigated. The TID and NBTI related degradations show an opposite trend as gate oxide scaling, which implies the different traps are activated during irradiation and NBTI stress. The radiation-induced traps can affect the NBTI effect of pMOSFET, especially for the ON bias irradiation. The irradiated I/O pMOSFET shows a smaller threshold voltage shift than the un-irradiated device under the same NBTI stress at the early stress stage. It may be contributed to the enhanced Fowler-Nordheim electron injection during NBTI stressing after ON bias irradiation. But the irradiation also increases the time exponent $n$ from 0.11 to 0.13 for Core pMOSFETs and from 0.18 to 0.20 for I/O devices. It means that the NBTI degradations become worse after ON bias irradiation in a long time scale. This phenomenon is attributed to the change of trap characteristics caused by irradiation. As a result, the NBTI lifetime of Core device is reduced by nearly three orders of magnitude and the lifetime of I/O device is reduced by five times after ON bias irradiation at the rated operating voltage.

The electrical characteristics and low-frequency noise (LFN) of AlGaN/GaN high-electron-mobility transistors (HEMTs) after 3-MeV proton irradiation up to a total dose of 5.0 $\times 10^{14}$ p/cm2 have been studied in this article. The devices experienced a 14.6% decrease in the saturation current, a 0.35-V positive shift in the threshold voltage ( $V_{\mathrm {th}}$ ), and a significant decrease in the reverse gate leakage current after 3-MeV proton irradiation. Extracted by the LFN method, the flat-band voltage noise power spectral density ( $S_{{V{\textrm {fb}}}}$ ) increases from 4.112 $\times \,\,10^{-12}\,\,\cdot $ Hz−1 to $5.603\times 10^{-12}\,\,\cdot $ Hz−1, and the trap density increases from $2.79\times 10^{17}$ to $3.84\times 10^{17}$ cm $^{-3}\,\,\cdot $ eV−1 after the radiation. The main degradation mechanism is considered to be the increase of negatively charged trap density in the channel, which depletes more electrons and reduces the carrier mobility in the channel 2-D electron gas (2DEG). We also extracted the radiation-induced trapped charge density according to the theoretical calculation; the result is consistent with the LFN measurement.

The negative bias temperature instability (NBTI) mechanisms for Core and input/output (I/O) devices from a 130 nm partially-depleted silicon on insulator (PDSOI) technology are investigated. The I/O device degrades more than the Core device under the same stress electric field due to the different gate oxide processes in these two types of devices. Both the oxide trap charge and interface trap lead to the transfer characteristics degradations of the device after NBTI. While the near interfacial traps result in the increase of low frequency noise (LFN). The trap densities near the silicon/gate oxide interface introduced by stress are extracted using the LFN method. NBTI-induced gate current increase is observed for Core device, but not for I/O device. It is result from the enhanced tunneling process, which is induced by the increase of electric field in the gate oxide after charge trapping at or near the channel interface. The gate width and length dependences of NBTI are observed. The enhanced NBTI degradation observed in short channel and narrow channel device is result from the enhanced NBTI effect at channel edge regions. The larger hole concentration is a main cause of the more serious NBTI degradation at the channel edge regions, including the nearby region of STI sidewall along the channel width direction and the gate edge region along the channel length direction. This conclusion is also verified by the TCAD simulations.

Neutron-induced secondary ions and their contribution to a single-event upset (SEU) in SRAM are investigated by Geant4 and TCAD simulations. It proves that the maximum linear energy transfer (LET) values of secondary ions produced by neutron–nuclear reactions can be as high as 31.5MeV-cm2/mg, while the LET value of 99.8% secondary ion is 2 MeV-cm2/mg could induce an SEU in this 65-nm SRAM. Then, these results are used to calculate the atmospheric neutron-induced soft-error rate (SER). The calculated SER is verified by field testing and 14-MeV neutron-accelerated testing.

Real-time soft error rate of 65-nm QDRII+ static random access memory was measured on the Tibetan-plateau with an altitude of 4300 m. Error types including single-bit upset (SBU), multiple-cell upset (MCU), and burst errors were observed. The MCU ratio is 23%, with a maximum size of nine cells. Majority of the MCU events are vertically oriented along the well stripes. Monte Carlo simulations were further performed to study the characteristics of the neutron-induced secondary ions. Diverse secondary ion species, from the proton to Re, were found, which were significantly affected by the presence or absence of the tungsten layer. The impact of neutron energy on the linear energy transfer (LET), range, and deposited charge of secondary ions in the sensitive volume was revealed.

Ion source development over the last 20 years at the IMP is reviewed. For versatile purposes, several types of ion sources have been involved in the research and development work at the IMP, i.e., the highly charged ECR (Electron Cyclotron Resonance) ion source, intense microwave ion source or the 2.45 GHz intense beam ECR ion source, and laser ion source (LIS). In the development of ECR ion sources, SECRAL (Superconducting ECR ion source with Advanced design in Lanzhou), Lanzhou ECR ion source, and Lanzhou all permanent magnet ECR ion source series have been made, which can cover the operation microwave frequency range of 10–28 GHz. The LIS with an Nd:YAG laser with a maximum output energy of 8 J in 8 ns pulse duration has been developed for very intense short pulse ion beams from solid materials such as C, Ti, Ni, Ag, and so on. Microwave ion sources have been built to produce intense pulsed or direct current beams from several mA to 100 mA for either high intensity accelerators or applications. This paper will give an overview of the high intensity ion source development at the IMP, especially on the recent progress and new results, such as the status of the fourth generation ECR ion source (first fourth generation ECR ion source), the production of recorded highly charged ion beams with SECRAL sources, key technology research studies, and so on.

Single-event upset sensitivity of 55- and 180-nm SRAM devices with error detection and correction (EDAC) exhibits obvious ion flux and scrubbing time dependence. On-orbit soft error rates (SERs) of EDAC SRAM devices are extrapolated from accelerator heavy-ion data and compared with rectangular parallelepiped-predicted SER, based on an experimentally verified formula. It is found that on-orbit SER of EDAC SRAM is contributed by both the memory array and the EDAC circuitry. This method can guide the optimization of EDAC SRAM hardening strategy and also the on-orbit hardness assurance.

The dependence of single event upset (SEU) on heavy ion energy was investigated for partially depleted silicon-on-insulator static random access memories. An unexpected phenomenon has been shown that the SEU cross sections decrease 70% with the increase of 12C ion linear energy transfer (LET) from 1.7 to 3.0 MeV/(mg/cm2). Furthermore, data from angled irradiations show that the SEU cross sections almost remain unchanged with the increase of effective LET in the subthreshold LET region. Geant4 simulation indicates that this anomalous trend of SEU cross sections is mainly attributed to energy effects of nuclear reactions between primary ions and material atoms. The SEU cross sections at subthreshold LET values are closely related to the energy of incident ions. Secondary Mg and Al ions produced by primary 12C ion nuclear reactions are the main ions to introduce the SEUs. A method is proposed for calculating the SEU cross sections induced by low LET heavy ions. The SEU cross sections calculated by Geant4 simulation with low LET heavy ions match well with the experimental results. The energy dependence of SEUs produced by low LET heavy ions implies that at accelerator-based SEU tests, the high-energy heavy ions with low LETs need to be utilized to estimate the contribution of indirect ionization to SEU cross sections for hardened devices with high-LET thresholds.

The 6T SRAM cell with fast access speed and silicon–oxide–nitride–oxide–Silicon (SONOS) cell with nonvolatility in a 130-nm commercial-off-the-shelf (COTS) nonvolatile SRAM (NVSRAM) is exposed to heavy ion irradiation under different test conditions. In 6T SRAM mode, the influence of linear energy transfer (LET), supply voltage, ambient temperature, and periphery circuits on single-event effects (SEE) is studied and analyzed. The anomaly of multiple upsets proportion with increasing the LET value may be ascribed to the difference of ion track structure. The observed nonmonotonic relationship between the upset cross section and supply voltage can be explained by a competing mechanism of critical charge and collected charge in a sensitive node. In SONOS nonvolatile mode, the upset threshold of 60.9 MeV/(mg/cm2) and two types of errors are observed. The recoverable upset error may be caused by ion-induced discharge of nonvolatile cell and the hard error that can be annealed to vanish in room temperature probably results from the ion-induced charge trapping in oxide. The above results show that the 6T SRAM cell in this NVSRAM is vulnerable to SEE, whereas the SONOS nonvolatile cell is quite resistant. Based on the prediction of space upset rate, the potential applications and issues of this COTS NVSRAM and deep sub-micrometer SONOS process in space component are discussed.

Two radiation hardening processes for shallow trench isolation (STI), i.e., Si+ implantation and STI oxide nitridation are investigated, including the impact on nominal electrical characteristics and radiation hardness. The total ionizing dose effects of the nMOS devices are proved to be sensitive to the STI radiation hardening process conditions. There are optimum process conditions to achieve the best effectiveness of radiation hardening. Then, a 130-nm radiation-hardened PDSOI technology has been developed. The radiation hardness is verified by static random access memories with small storage capacities.