Effects of proton irradiation at different incident angles on InAlAs/InGaAs InP-based HEMTs

InP-based high electron mobility transistors(HEMTs) will be affected by protons from different directions in space radiation applications. The proton irradiation effects on InAlAs/InGaAs hetero-junction structures of InP-based HEMTs are studied at incident angles ranging from 0 to 89.9° by SRIM software. With the increase of proton incident angle, the change trend of induced vacancy defects in the InAlAs/InGaAs hetero-junction region is consistent with the vacancy energy loss trend of incident protons. Namely, they both have shown an initial increase, followed by a decrease after incident angle has reached 30°. Besides, the average range and ultimate stopping positions of incident protons shift gradually from buffer layer to hetero-junction region, and then go up to gate metal. Finally, the electrical characteristics of InP-based HEMTs are investigated after proton irradiation at different incident angles by Sentaurus-TCAD. The induced vacancy defects are considered self-consistently through solving Poisson's and current continuity equations. Consequently, the extrinsic transconductance, pinch-off voltage and channel current demonstrate the most serious degradation at the incident angle of 30?, which can be accounted for the most severe carrier sheet density reduction under this condition.     

Photo-transmutation based on resonance γ-ray source

High intensity γ-ray source can be obtained through resonance reaction induced by protons. In this work, the possibility of using such high intensity MeV-range γ-ray source to transmute nuclear waste is investigated through Mont Carlo simulation.~(197) Au(γ, n)~(196)Au experiment is performed to obtain the transmutation rate and compared with the simulation result. If the current of the proton beam is 10 mA at the resonance energy of 441 keV, with the γ photons emitted from~7 Li(p, γ)~8 Be, then the corresponding transmutation yield for~(129)I in 2π direction can reach 9.4 × 10~9 per hour. The result is compared with that of LCS γ-ray source.     

Proton irradiation effect on SCDs

The Low Energy X-ray Telescope is one of the main payloads on the Hard X-ray Modulation Telescope satellite.Swept charge devices(SCDs)are selected as detectors for the Low Energy X-ray Telescope.As SCDs are sensitive to proton irradiation,irradiation tests were carried out on the HI-13 accelerator at the China Institute of Atomic Energy.The beam energy was measured to be 10 MeV at the SCD.The proton fluence delivered to the SCD was 3×108protons/cm2over two hours.By comparing the performance before and after irradiation,it is concluded that proton irradiation affects both the dark current and the charge transfer inefficiency of the SCD.The energy resolution of the proton-irradiated SCD is 212 eV@5.9 keV at-60?C,while it before irradiated is 134 eV.Moreover,better performance can be reached by lowering the operating temperature of the SCD in orbit.     

Proton radiation effect on GaAs/AlGaAs core–shell ensemble nanowires photo-detector

We demonstrate that the GaAs/AlGaAs nanowires(NWs) ensemble is fabricated into photo-detectors. Current–voltage(I–V) characteristics are measured on Ga As/Al Ga As core–shell ensemble NW photo-detectors at room-temperature before and after 1-MeV proton irradiation with fluences from 1.0 × 10~(13) cm~(-2) to 5.0 × 10~(14) cm~(-2). The degradation of photocurrent suggests that the point defects induced by proton radiation could cause both carrier lifetime and carrier mobility to decrease synchronously. Comparing with a GaAs quantum well, the degradations of light and dark current for the irradiated NWs photo-detector indicate that NWs material is a preferable potential candidate for space applications.     

Effect of vacancy defect clusters on the optical property of the aluminium filter used for the space solar telescope

We investigate the microstructures of the pure aluminium foil and filter used on the space solar telescope, irradiated by photons with different doses. The vacancy defect clusters induced by proton irradiation in both samples are characterized by transmission electron microscopy, and the density and the size distribution of vacancy defect clusters are determined. Their transmittances are measured before and after irradiating the samples by protons with energy E=100~keV and dose φ =6× 10¹¹/mm². Our experimental results show that the density and the size of vacancy defect clusters increase with the increase of irradiation doses in the irradiated pure aluminium foils. As irradiation dose increases, vacancies incline to form larger defect clusters. In the irradiated filter, a large number of banded void defects are observed at the agglomerate boundary, which results in the degradation of the optical and mechanical performances of the filter after proton irradiation.     

Laser-induced damage threshold in HfO_2/SiO_2 multilayer films irradiated by β-ray

Post-processing can effectively improve the resistance to laser damage in multilayer films used in a high power laser system. In this work, HfO_2/SiO_2 multilayer films are prepared by e-beam evaporation and then β-ray irradiation is employed as the post-processing method. The particle irradiation affects the laser induced damage threshold(LIDT),which includes defects, surface roughness, packing density and residual stress. The residual stress that is relaxed during irradiation changes from compressive stress into tensile stress. Our results indicate that appropriate tensile stress can improve LIDT remarkably. In view of the fact that LIDT rises from 8 J/cm~2 to 12 J/cm~2, i.e., 50% increase, after the film has been irradiated by 2.2×10~(13)/cm~2 β-ray, the particle irradiation can be used as a controllable and desirable postprocessing method to improve the resistance to laser induced damage.     

A comparison of ionizing radiation damage in CMOS devices from ^60Co gamma rays,electrons and protons

Radiation hardened CC4007RH and non-radiation hardened CC4011 devices were irradiated using ^60Co gamma rays, 1 MeV electrons and 1-9 MeV protons to compare the ionizing radiation damage of the gamma rays with the charged particles. For all devices examined, with experimental uncertainty, the radiation induced threshold voltage shifts （△Vth） generated by ^60Co gamma rays are equal to that of 1 MeV electron and 1-7 MeV proton radiation under 0 gate bias condition. Under 5 V gate bias condition, the distinction of threshold voltage shifts （△Vth） generated by ^60Co gamma rays and 1 MeV electrons irradiation are not large, and the radiation damage for protons energy the proton has, the less serious below 9 MeV is always less than the radiation damage becomes. that of ^60Co gamma rays. The lower     

Impact of the displacement damage in channel and source/drain regions on the DC characteristics degradation in deep-submicron MOSFETs after heavy ion irradiation

This paper mainly reports the permanent impact of displacement damage induced by heavy-ion strikes on the deep-submicron MOSFETs.Upon the heavy ion track through the device,it can lead to displacement damage,including the vacancies and the interstitials.As the featured size of device scales down,the damage can change the dopant distribution in the channel and source/drain regions through the generation of radiation-induced defects and thus have significant impacts on their electrical characteristics.The measured results show that the radiation-induced damage can cause DC characteristics degradations including the threshold voltage,subthreshold swing,saturation drain current,transconductance,etc.The radiation-induced displacement damage may become the dominant issue while it was the secondary concern for the traditional devices after the heavy ion irradiation.The samples are also irradiated by Co-60 gamma ray for comparison with the heavy ion irradiation results.Corresponding explanations and analysis are discussed.     

Correlation between Displacement Damage Dose and Proton Irradiation Effects on GaInP/GaAs/Ge Space Solar Cells

The irradiation effects of 0.28-2.80 MeV protons on GalnP/GaAs/Ge solar cells have been analysed, and then correlated with the displacement damage dose. The results of I-V and spectral response measurements, combined with the SRIM-derived vacancies produced rates, show that the degradation of the solar cells is largely determined by the displacement damage of the GaAs sub-cell. Thus the SRIM-derived NIEL values for protons in the GaAs sub-cell are used to calculate the displacement damage dose. It is shown that the irradiation effects of the solar cells caused by protons at different energies are correlated well with the aid of displacement damage dose.     

Irradiation Effects on the Retention of Hydrogen in Al_2O_3

Substantial defects are produced in Al_2O_3 by 4 MeV Au ion irradiation with a fluence of 4.4 × 10~(15) cm~(-2).Rutherford backscattering spectrometry/channeling and cross-sectional transmission electron microscopy methods are used to investigate the irradiation damage.The 190 keV H ions with a fluence of 1 × 10~(17) cm~(-2) are used for implanting pristine and Au ion irradiated Al_2O_3 to explore the irradiation damage effects on the hydrogen retention in Al_2O_3.The time-of-flight secondary ion mass spectrometry method is used to obtain the single hydrogen depth profile and ions mass spectra(IMS),in which we find that implanted hydrogens interacted with defects produced by Au ion irradiation.In IMS,we also obtain the hydrogen retention at a certain depth.Comparing the hydrogen retention in different Al_2O_3 samples,it is concluded that the irradiation damage improves the tritium permeation resistance property of Al_2O_3 under given conditions.This result means that Al_2O_3 may strengthen its property of reducing tritium permeation under the harsh irradiation environment in fusion reactors.     

Effects of Pre-exposure Mouse Pituitary with Low-dose ^60Co γ-ray on Growth Hormone （GH） and Body Mass Induced by Subsequent High-dose Irradiation

The pituitary of the B6C3F1 hybrid strain mice were irradiated with 0.05 Gy of ^60Co γ-ray as the pre-exposure dose (D1), and were then irradiated with 2 Gy of ^60Co γ-ray as challenging irradiation dose (D2) at 4h after per-exposure. Body weight and serum growth hormone (GH) were measured at 35th day after irradiation. The results showed that irradiation of mouse testes with 2 Gy of ^60Co γ-ray significantly diminished mousebody weight and level of serum GH (Table). Pre-exposure with a low-dose (0.05 Gy) of ^60Co γ-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by subsequent a high-dose (2 Gy) irradiation (Table). The data suggested that low-dose ionizing irradiation can induce adaptive responses to the harmful effects of pituitary by subsequent high-dose exposure.     

The effects of ⁶⁰Co γ-ray irradiation on the DC characteristics of enhancement-mode AlGaN/GaN high-electron-mobility transistors

The effects of 60Co γ-ray irradiation on the DC characteristics of AlGaN/GaN enhancement-mode high-electron-mobility transistors (E-mode HEMTs) are investigated. The results show that having been irradiated by 60Co γ-rays at a dose of 3 Mrad (Si), the E-mode HEMT reduces its saturation drain current and maximal transconductance by 6% and 5%, respectively, and significantly increases both forward and reverse gate currents, while its threshold voltage is affected only slightly. The obvious performance degradation of E-mode AlGaN/GaN HEMTs is consistent with the creation of electronegative surface state charges in the source-gate spacer and gate-drain spacer after being irradiated.     

The effects of 60Co γ-ray irradiation on the DC characteristics of enhancement-mode AlGaN/GaN high-electron-mobility transistors

The effects of 60Co γ-ray irradiation on the DC characteristics of AlGaN/GaN enhancement-mode high-electron-mobility transistors (E-mode HEMTs) are investigated. The results show that having been irradiated by 60Co γ-rays at a dose of 3 Mrad (Si), the E-mode HEMT reduces its saturation drain current and maximal transconductance by 6% and 5%, respectively, and significantly increases both forward and reverse gate currents, while its threshold voltage is affected only slightly. The obvious performance degradation of E-mode AlGaN/GaN HEMTs is consistent with the creation of electronegative surface state charges in the source-gate spacer and gate-drain spacer after being irradiated.     

Effect of defects properties on InP-based high electron mobility transistors

The performance damage mechanism of InP-based high electron mobility transistors(HEMTs) after proton irradiation has been investigated comprehensively through induced defects.The effects of the defect type, defect energy level with respect to conduction band ET, and defect concentration on the transfer and output characteristics of the device are discussed based on hydrodynamic model and Shockley–Read–Hall recombination model.The results indicate that only acceptorlike defects have a significant influence on device operation.Meanwhile, as defect energy level ETshifts away from conduction band, the drain current decreases gradually and finally reaches a saturation value with ETabove 0.5 eV.This can be attributed to the fact that at sufficient deep level, acceptor-type defects could not be ionized any more.Additionally,the drain current and transconductance degrade more severely with larger acceptor concentration.These changes of the electrical characteristics with proton radiation could be accounted for by the electron density reduction in the channel region from induced acceptor-like defects.     

Optical sensors based on the NiPc-CoPc composite films deposited by drop casting and under the action of centrifugal force

In this study, solution processed composite films of nickel phthalocyanine(NiPc) and cobalt phthalocyanine(CoPc)are deposited by drop casting and under centrifugal force. The films are deposited on surface-type inter-digitated silver electrodes on ceramic alumina substrates. The effects of illumination on the impedance and capacitance of the NiPc–CoPc composite samples are investigated. The samples deposited under centrifugal force show better conductivity than the samples deposited by drop casting technique. In terms of impedance and capacitance sensitivities the samples fabricated under centrifugal force are more sensitive than the drop casting samples. The values of impedance sensitivity(S_z)are equal to(-1.83) M?·cm~2/mW and(-5.365) M?·cm~2/mW for the samples fabricated using drop casting and under centrifugal force, respectively. Similarly, the values of capacitance sensitivity(S_c) are equal to 0.083 pF·cm~2/mW and 0.185 pF·cm~2/mW for the samples fabricated by drop casting and under centrifugal force. The films deposited using the different procedures could potentially be viable for different operational modes(i.e., conductive or capacitive) of the optical sensors. Both experimental and simulated results are discussed.     

Effects of Pre-exposure of Mouse Pituitary with Low-dose ^60Co γ-ray on Male Reproductive Endocrine Capacity Induced by Subsequent High-dose Irradiation

To investigate the effects of pre-exposure of mouse pituitary with low-dose ^60Co γ-ray on male reproductive endocrine capacity induced by subsequent high-dose irradiation, the pituitary of the B6C3F1 hybrid strain male mice were irradiated with 0.05 Gy of ^60Co γ-ray as the pre-exposure dose (D1), and were then irradiated with 2 Gy of ^60Co γ-ray as challenging irradiation dose (D2) at 4 h after per-exposure. Pituitary gonadotroping hormones --follicle-stimulating hormone (FSH) and luterinzing hormone (LH), serum testosterone, testis weight and sperm count were measured at 35th day after irradiation.     

Influence of Total Ionizing Dose Irradiation on Low-Frequency Noise Responses in Partially Depleted SOI nMOSFETs

Total ionizing dose effect induced low frequency degradations in 130 nm partially depleted silicon-on-insulator(SOI) technology are studied by ~(60) Co γ-ray irradiation. The experimental results show that the flicker noise at the front gate is not affected by the radiation since the radiation induced trapped charge in the thin gate oxide can be ignored. However, both the Lorenz spectrum noise, which is related to the linear kink effect(LKE) at the front gate, and the flicker noise at the back gate are sensitive to radiation. The radiation induced trapped charge in shallow trench isolation and the buried oxide can deplete the nearby body region and can activate the traps which reside in the depletion region. These traps act as a GR center and accelerate the consumption of the accumulated holes in the floating body.It results in the attenuation of the LKE and the increase of the Lorenz spectrum noise. Simultaneously, the radiation induced trapped charge in the buried oxide can directly lead to an enhanced flicker noise at the back gate. The trapped charge density in the buried oxide is extracted to increase from 2.21×10~(18)eV~(-1)cm~(-3) to 3.59×10~(18)eV~(-1)cm~(-3) after irradiation.     

Total ionizing dose effects in pinned photodiode complementary metal-oxide-semiconductor transistor active pixel sensor

A pinned photodiode complementary metal–oxide–semiconductor transistor(CMOS) active pixel sensor is exposed to ~(60)Co to evaluate the performance for space applications. The sample is irradiated with a dose rate of 50 rad(SiO_2)/s and a total dose of 100 krad(SiO_2), and the photodiode is kept unbiased. The degradation of dark current, full well capacity,and quantum efficiency induced by the total ionizing dose damage effect are investigated. It is found that the dark current increases mainly from the shallow trench isolation(STI) surrounding the pinned photodiode. Further results suggests that the decreasing of full well capacity due to the increase in the density, is induced by the total ionizing dose(TID) effect, of the trap interface, which also leads to the degradation of quantum efficiency at shorter wavelengths.     

A study of radiation effects of 9 and 12 MeV protons on Chinese CMOS image sensor degradation

The 9 and 12 MeV proton irradiations of the Chinese CMOS Image Sensor in the fluence range from 1×109to 4×1010 cm-2and 1×109 to 2×1012 cm-2 have been carried out respectively. The color pictures and dark output images are captured, and the average brightness of dark output images is calculated. The anti-irradiation fluence thresholds for 9 and 12 MeV protons are about 4×1010 and 2×1012 cm-2, respectively. These can be explained by the change of the concentrations of irradiation-induced electron-hole pairs and vacancies in the various layers of CMOS image sensor calculated by the TRIM simulation program.