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The synergetic effects of total ionization dose and high-temperature stress of SOI FinFETs are investigated under ON-state bias condition. The experiments and TCAD simulations are employed to analyze the influence of different trapped-charges in the gate and buried oxide on the threshold voltage and mobility variations on the ON-state current of the devices. Results show that the threshold voltage degradation worsens for n-SOI FinFETs but weakens for the p-SOI FinFETs. Also, the ON-state current of n-SOI FinFETs is significantly enhanced while the change of p-SOI FinFETs is weak under the synergetic effects. The threshold voltage degradation induced by synergetic effects for both n- and p-type SOI FinFETs can exceed the linear superposition of the two types of stresses, which may be related to the thermal release of trapped charges in the gate oxide. The enhanced degradation in the n-SOI FinFETs compared with the p-SOI FinFETs may result from the shallow energy level electron traps in HfO2. Besides, for both n- and p-type SOI FinFETs, the ON-state current variations under the synergetic effects depend on the competitive process of threshold voltage variation and the mobility fluctuation.

The dependence of temperature and back-gate bias on single-event upset (SEU) sensitivity is investigated based on a 0.2- $\mu \text{m}$ double silicon-on-insulator (DSOI) technology. At room temperature, an obvious decrease in SEU cross section with the negative back-gate bias is experimentally observed for a DSOI static random access memory (SRAM). The physical mechanism of single-event effect (SEE) is explained through technology computer-aided design (TCAD) simulations. TCAD simulations were also performed to explain the impact of back-gate bias on charge collection and full width at half maximum (FWHM) of the pulsewidth at various temperatures. Both charge collection and FWHM of the pulsewidth increase significantly with temperature rising from 240 to 400 K. It is demonstrated that the SEU threshold linear energy transfer (LET) for a DSOI 6T SRAM cell decreases with an increase in temperature. Compared with a fully depleted SOI (FDSOI) technology, the unique independent back-gate bias scheme for a DSOI SRAM cell exhibits higher tolerance to SEU. At 400 K, it is found that the SEU threshold LET (LETth) for a DSOI 6T SRAM cell increases by 12.5% with back-gate bias of nMOS reduced from 0 to −15 V.

The effects of the white-light X-ray and 170-keV proton beam irradiation on the electrical and optical characteristics of the InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) are analyzed and compared. Different from the negative effects of the proton irradiation, the X-ray irradiation shows positive effects on the LEDs’ performance. In detail, after the 100 Mrad(Si) X-ray irradiation, the p-n junction resistance decreases from the original 2.51 to $2.08~\Omega $ , the light output power increases from 170 to 203 mW (at a forward voltage of 3.2 V), and the maximal external quantum efficiency (EQE) increases from 56.7% to 61.8%. Based on the ABC model fittings, both the Shockley–Read–Hall recombination rate and the radiative recombination rate in the MQWs are improved by the X-ray irradiation. The Hall effect measurements reveal the chemical bond breaking of the Mg-H complex in the p-type GaN. Therefore, the improvement of the LED by the X-ray irradiation should be caused by the chemical bond variations of the defect-related complex in the MQWs and the Mg-H complex in the p-type GaN.

Influences of 170-keV protons beam irradiation on the static and dynamic properties of blue light InGaN/GaN multiple quantum wells (MQWs) microlight-emitting diodes (Micro-LEDs) were investigated. It was interesting to find out that, although threshold voltage and light output power of Micro-LEDs deteriorated after proton irradiation, a 3-dB bandwidth was greatly improved. In quantitative terms, at the forward current density of 1 kA/cm2, 3-dB bandwidth increased from original 7.34 to 119.74 MHz when Micro-LED exposed to proton beam with the fluence of $5\times 10^{14}$ p/cm2. Based on the frequency response data analysis, differential carrier lifetimes of Micro-LEDs, including Shockley–Read–Hall (SRH) lifetime and differential radiation recombination lifetime, were compared. The results pointed out that both SRH and recombination lifetimes became shorter after proton irradiation, indicating that competition between the nonradiative and radiative recombination processes was enhanced by proton beam. To reveal the origination of the 3-dB bandwidth improvement, photoluminescence (PL) and time-resolved PL (TRPL) spectrums of Micro-LEDs were measured. MQWs’ PL spectrum with a peak wavelength of 450 nm was observed and its intensity decreased as proton fluence increasing. Meanwhile, a PL peak at 550 nm, which was well known as defect-related PL spectrum, was enhanced by proton irradiation, especially at a proton fluence of $5\times 10^{13}$ and $5\times 10^{14}$ p/cm2, proving the increase of defects in epitaxial thin films as proton fluence increasing. In the TRPL experimental study, the nonradiative recombination lifetime decreased with proton fluence, which was consistent with the results analyzed by frequency response. Overall, the improvement of 3-dB bandwidth could be mainly attributed to the decrease of carrier lifetime in MQWs, which were caused by the generation of defects due to the atom displacement effect of proton irradiation.

Correlated double sampling (CDS) circuits are essential to processing the X-ray charge-coupled devices (CCDs) that have been widely used in the modern X-ray astronomical field. For timing observations, both energy resolution and timing resolution are of great importance. We are developing the XCR4C application-specific integrated circuit (ASIC), which is a fully customized four-channel radiation-hardened CDS ASIC targeting the readout of X-ray CCDs, for future space astronomical missions. The ASIC is implemented in a differential switched-capacitor architecture, making it highly linear, low power, immune to common-mode noise and interferences, as well as easily configurable. To combat the harsh low-earth-orbit space environment, some radiation-hardening techniques are applied, including the process hardening method, even-finger double-side bulk butting, and pseudo-double guard ring layout techniques. The XCR4C ASIC was fabricated with 0.35- $\mu \text{m}$ 2P4M CMOS technology with an epitaxial layer. The ASIC achieves a maximum 23-ppm integral nonlinearity and 5.8 e− rms equivalent noise charge under a typical 1-MHz pixel rate and only consumes 50 mW approximately from a single 3.3-V supply voltage. The results from radiation hardness assurance testing show that the ASIC has at least a total ionizing dose tolerance of 300 krad(Si), and no single-event latchup has been found up to a linear energy transfer of $81.35~\text {MeV}\cdot \text {cm}^{2}$ /mg with a total fluence up to $1.68\times 10^{7}$ ions/cm2.

Fully depleted (FD) silicon-on-insulator (SOI) nMOSFETs fabricated using 0.2- $\mu \text{m}$ SOI technology with external body contact (EBC) and floating body (FB) structures are irradiated up to 500 krad(Si) using 60Co gamma rays under the transmission gate (TG) and OFF bias conditions, respectively. The threshold voltage shift of the back transistors due to radiation-induced charge trapping in the buried oxide (BOX) is used to characterize the total dose response of irradiated back transistors. The results indicate that, overall, the TG biased EBC transistors with various gate lengths are more sensitive to the total dose radiation than the OFF biased FB counterparts at low dose levels. Furthermore, for the shorter gate transistors with a supply voltage of 1.8 V, a relatively complex correlation exists between the total dose response and the gate length. In particular, the back transistor of the TG biased 0.20- $\mu \text{m}$ 1.8-V EBC transistor reveals smaller threshold voltage shifts than the OFF biased counterpart at approximately 500 krad(Si) because of the saturation of its threshold shift with increased doses, and a similar radiation response is observed for the TG biased 0.35- $\mu \text{m}$ EBC transistor with a supply voltage of 2.5 V. We found that the 2.5-V back transistors exhibited greater radiation hardness than the 1.8-V counterparts with the same bias configuration in most cases.

This paper investigates the effect of total ionizing dose radiation on back-gate interface traps in SOI NMOSFETs. The concentration and energy distribution of interface traps at Si/SiO2 back-gate interface of SOI NMOSFETs during irradiation are studied by the direct-current current-voltage technique. When transistors are subjected to radiation, DCIV bulk current increases. The calculated results suggest that the interface trap density increases and its equivalent energy level is far away from the midgap with irradiation dose increasing, which can be explained by the energy distribution of interface traps. The interface trap energy density DIT(EIT) as a function of the energy level EIT has been obtained by the least square optimization and shows the typical “U-shape”distribution. In detail, the rising humps at equivalent energy level in DIT(EIT) curves are due to Si-H bonds that are broken down after irradiation, which corresponds to the increasing trap density. Moreover, it is found that the energy level of interface traps is redistributed after irradiation. The peak of humps in DIT(EIT) curves occurs at the farther energy level with the increase of dose, which is similar to the equivalent energy level. It might arise from the shallow energy level of interface traps induced by radiation.

High-resolution X-ray diffraction, temperature-dependent photoluminescence (PL), time-resolved PL, and positron annihilation spectroscopy are employed to investigate the degradation mechanism of InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) under silicon ion irradiation. Reduction of the quantum-confined Stark effect due to crystalline strain relaxation, enhancement of indium localization due to thermal spike, generation of nonradiative recombination centers (NRCs), and carrier removal effect due to atom displacement are revealed to be critical factors in LEDs postirradiation performance. New NRCs are proven to be the main reason for the degradation of the internal quantum efficiency of MQWs. The increase of the threshold voltage and leakage current in LEDs are caused by the carrier removal effect and new defects in bandgap induced by radiation. In addition, new NRCs are found to appear earlier than indium localization and carrier removal effect with increasing silicon ion fluence. Atom displacement defects are revealed to be located mainly in p-type GaN and MQWs layers. Radiation-induced nitrogen vacancies are considered compensation donors in p-type GaN, whereas all other nitrogen and gallium-related defects are NRCs in MQWs.

The total ionizing dose response of bulk nFinFETs with multiple gate lengths and multiple fins is investigated for on-state bias condition. Experiments and Technology Computer Aided Design simulations were performed to analyze the effect of the trapped charges in the gate oxide and shallow trench isolation (STI) oxide on the threshold voltage and transconductance of the devices. The increases in the threshold voltage and transconductance are observed after X-ray irradiation. The positive shift of the threshold voltage is caused by the net negative charges trapped in the gate oxide. The simulation results show that the trapped holes in the STI oxide reduce the electric field and increase the electron mobility in channel near the fin bottom, which is the major contribution to the increased transconductance. An interesting phenomenon was also observed that the threshold voltage continues to increase during the annealing process, whereas the transconductance decreases. These results suggest that there may also be a small amount of trapped holes in gate oxide during irradiation, and those trapped holes are compensated by electrons transporting from the silicon during the anneal, leading to further positive shift of the threshold voltage. Moreover, the decrease in transconductance is mainly introduced by the neutralization of the trapped holes at STI/silicon interface.

The existence of buried oxide (BOX) layer and the strong coupling effect between the front and back channels can worsen the radiation-induced degradation on fully depleted silicon-on-insulator (FDSOI) device. To mitigate the radiation impact, a new structure named double SOI is introduced in this paper. This new structure exhibits potential benefits of reducing the radiation-induced degradation effectively and independently, thanks to the additional electrode, which can be used to control the internal electrical field of the BOX layer. With this structure, FDSOI device parameter degradation due to total dose is studied, and some abnormal phenomena, such as the transconductance hump and the mobility enhancement, are observed and discussed. Sentaurus TCAD simulations are used for further analysis. Moreover, the impact of negative back-gate bias to transistor parameter degradation is investigated, and an improved back-gate compensation strategy is proposed. Technology improvement such as thinning the BOX on total ionizing dose (TID) amelioration is also discussed with TCAD simulation.