Radiation-induced Trapping Research Articles

Study on annealing effect of bipolar transistors at different temperatures after total dose irradiation

The article investigates the annealing process of bipolar transistors after total dose irradiation, using the GLPNP transistor as the research object. After total dose irradiation, room temperature and high temperature annealing tests were carried out. Gummel curve, GS curve and SS curve of bipolar transistor are obtained by I/V scanning, gate scanning and sub-threshold scanning. The evolution behavior of radiation-induced oxide trap charges and interface state damage defects during annealing of bipolar transistors at different temperatures was quantitatively analyzed by different microscopic defect characterization methods. Generally speaking, this study is of great significance to better understand the recovery mechanism of electrical properties of bipolar transistors during annealing after total dose irradiation, and can provide reference for the design, application and radiation-hard of transistors.

MoS2/PEDOT:PSS nanocomposite films for deep UV sensing: role of the radiation-induced trapping and localization of charges

MoS2/PEDOT:PSS nanocomposite films for deep UV sensing: role of the radiation-induced trapping and localization of charges

Investigation of total ionizing dose effects in 4H–SiC power MOSFET under gamma ray radiation

In this work, the gamma ray radiation-induced total ionizing dose (TID) effects in SiC power MOSFETs are investigated. The transistor characteristics, such as transfer curve, output curve, drain-source ON-state resistance and terminal capacitance, are characterized to quantify the radiation tolerance. The threshold voltage is found to be sensitive to radiation and decreases with radiation dose increasing. An increased drive current and decreased drain-source ON-state resistance are resulted due to the decreased threshold voltage. The increased gate input capacitance exists after radiation. Verified in Sentaurus TCAD 2D simulation, the radiation-induced trap charge and interface states at SiO2/SiC interface are found to dominate the degradation of electrical behaviors in SiC power MOSFET.

Study on Total Ionizing Dose Effect of Silicon Carbide Metal Oxide Semiconductor Field-Effect Transistors at High and Low Dose Rates

The total ionizing dose (TID) radiation effect of silicon carbide metal oxide semiconductor field-effect transistors (SiC MOSFETs) was investigated at different dose rates. The influence of irradiation dose rate on the transfer characteristic curves of the devices was investigated. And the threshold voltage, oxide trap charge, interface state, and peak transconductance et al. were further extracted based on the transfer curve. The results show that the degradation degree of irradiated devices varies at different dose rates due to the different factors. The degradation of the device at high dose rate is due to the radiation-induced oxide trap charge in the gate oxide layer, while the reason of the degradation at low dose rate is the radiation-induced oxide trap charges and interface state simultaneously, which have opposite effects on the devices, and the degradation degree depends on the competition between the two.

Characteristics of noise degradation and recovery in gamma-irradiated SOI nMOSFET with in-situ thermal annealing

This paper demonstrates a procedure for complete in-situ recovery of on-membrane CMOS devices from total ionizing dose (TID) defects induced by gamma radiation. Several annealing steps were applied using an integrated micro-heater with a maximum temperature of 365 °C. The electrical characteristics of the on-membrane nMOSFET are recorded prior and during irradiation (up to 348 krad (Si)), as well as after each step of the in-situ thermal annealing. High-resolution current sampling measurements reveal the presence of oxide defects after irradiation, with a clear dominant single-trap signature in the random telegraph noise (RTN) traces. Drain current over time measurements are used for the trap identification and further for the defects' parameters extraction. The power spectral density (PSD) curves confirm a clear dominance of the RTN behavior in the low-frequency noise. A radiation-induced oxide trap is detected at 5.4 nm from the Si-SiO2 interface, with an energy of 0.086 eV from the Fermi level in the bandgap. After annealing, the RTN behavior vanishes with a further important reduction of flicker noise. Low-frequency noise measurements of the transistor confirmed the neutralization of oxide defects after annealing. The electro-thermal annealing of the nMOSFET allows a total recovery of its original characteristics after being severely degraded by radiation-induced defects.

Sensitivity and fading of irradiated RADFETs with different gate voltages

The radiation-sensitive field-effect transistors (RADFETs) with an oxide thickness of 400 nm are irradiated with gate voltages of 2, 4 and 6 V, and without gate voltage. A detailed analysis of the mechanisms responsible for the creation of traps during irradiation is performed. The creation of the traps in the oxide, near and at the silicon/silicon-dioxide (Si/SiO2) interface during irradiation is modelled very well. This modelling can also be used for other MOS transistors containing SiO2. The behaviour of radiation traps during postirradiation annealing is analysed, and the corresponding functions for their modelling are obtained. The switching traps (STs) do not have significant influence on threshold voltage shift, and two radiation-induced trap types fit the fixed traps (FTs) very well. The fading does not depend on the positive gate voltage applied during irradiation, but it is twice lower in case there is no gate voltage. A new dosimetric parameter, called the Golden Ratio (GR), is proposed, which represents the ratio between the threshold voltage shift after irradiation and fading after spontaneous annealing. This parameter can be useful for comparing MOS dosimeters.

Evaluation of total-ionizing-dose effects on reconfigurable field effect transistors and SRAM circuits

For the first time, this paper presents a qualitative analysis of the total-ionizing-dose effects on reconfigurable field effect transistors (RFETs) and the corresponding static random-access memory (SRAM) circuits based on 3D technology computer aided design simulations. The effects of various electrical biases and geometric parameters are investigated in detail. For n- and p-type programs, the threshold voltages (V TH) respectively decrease by 83 mV and increase by 57 mV after 40 Mrad (Si) of irradiation. Radiation-induced oxide trap charges in the spacer region near the source side are shown to mainly dominate the performance degradation in RFETs. The control gate voltage (V CG) and spacer length on the source side L S_Spacer are shown to have a significant influence on the total-ionizing-dose response, and a shorter L S_Spacer presents a stronger total-dose tolerance. When the RFETs in SRAMs suffer from a degraded V TH, the SRAM’s read static noise margin declines by 51.3 mV after 40 Mrad (Si) of irradiation. This work provides a radiation hardening foundation for the application of RFET technology in future extreme-environment electronics applications.

Новый сценарий кинетики зарядки диэлектриков при облучении электронами средних энергий

The goal of this paper is first to critical review the charging phenomena occurring during electron deposition in insulating materials. In this research we focus on the elucidation of the charging kinetics including the effects of the electron emission increasing and the electron-radiation defect creation. In order to avoid some misinterpretation and contradiction of the experimental results we include three fundamental key factors. The first, in the consideration we include the density of the initial (intrinsic) and radiation-induced trapping sites, second, we take into account the role of the primary thermalized electrons in the emission, and third, the charging phenomena in steady-state phase is regulated by the electronic filed, generated during charging.

Gate Bias and Length Dependences of Total Ionizing Dose Effects in InGaAs FinFETs on Bulk Si

We evaluate the total ionizing dose (TID) responses of InGaAs nMOS FinFETs with different gate lengths irradiated with 10-keV X-rays under different gate biases. The largest degradation after irradiation occurs at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> = -1 V. Radiation-induced trapped positive charge dominates the TID response of InGaAs FinFET transistors, consistent with previous results for InGaAs multifin capacitors. Shorter gate-length devices show larger radiation-induced charge trapping than longer gate-length devices, most likely due to the electrostatic effects of trapped charge in the surrounding SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> isolation and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> spacer oxides. The 1/f noise measurements indicate a high trap density and a nonuniform defect-energy distribution, consistent with a strong variation of effective border-trap density with surface potential.

Total-Ionizing-Dose Response of MoS2Transistors With ZrO2and h-BN Gate Dielectrics

The total-ionizing-dose response of few layer MoS2 transistors with ZrO2 or h-BN gate dielectrics is investigated under various bias conditions. Defects in MoS2 and surrounding dielectric layers significantly affect radiation-induced trapping. For devices with ZrO2 dielectrics, much larger negative Vth shifts and peak transconductance degradation are observed for irradiation under negative and ground bias than under positive bias. The h-BN devices exhibit positive threshold voltage shifts under negative-bias irradiation. For both ZrO2 and h-BN passivated devices, the peak transconductance degradation results from charge trapping at the surface of the MoS2 or in nearby oxides. Changes in defect energy distributions of MoS2 FETs during X-ray irradiation are characterized via temperature-dependent low-frequency noise measurements. Density functional theory calculations are performed to provide insight into the pertinent defects.

Comprehensive study on hot carrier reliability of radiation hardened H-gate PD SOI NMOSFET after gamma radiation

ABSTRACTThe authors perform gamma ray irradiation and hot carrier stress on RH H-Gate PD (partially depleted) SOI NMOSFETs as the experimental group and commercial strip-shaped gate PD SOI NMOSFETs as the control group. They analyse HCI degradation in samples and conclude that radiation could enhance HCI degradation in RH H-gate samples. Moreover, the mechanism is explained as the coupling effect between the front gate and back gate caused by TID radiation-induced trap charges in the buried oxide.

Comparative Study of Cryogenic Versus Room-Temperature Proton Irradiation of N-Channel CCDs and Subsequent Annealing

Two PLATO Teledyne-e2v CCD280 have been proton irradiated: one whilst operating at cold and the other unbiased at room temperature. We report on differences in the postirradiation hot pixel population, trap species, and charge transfer inefficiency (CTI), including after annealing. We demonstrate once more that proton irradiation performed at the charge-coupled device temperature of operation can show significant differences to the traditional room-temperature irradiation. The cold-irradiated detector shows a factor 2 greater radiation induced increase in dark current and a factor 3 to 4 greater increase in hot pixel numbers, however, the parallel CTI measured in the PLATO operating conditions is a factor 1.5 lower. Using the trap pumping technique, we provide distributions of radiation-induced trap release time constants at different temperatures, which can be used to identify the type of defects and estimate CTI in other operating conditions.

Gate Bias and Geometry Dependence of Total-Ionizing-Dose Effects in InGaAs Quantum-Well MOSFETs

The effects of total-ionizing-dose irradiation are investigated in HfO2/InGaAs quantum-well MOSFETs. Radiation-induced hole trapping is higher for irradiation under positive gate bias than under negative gate bias. Electrical stress-induced electron trapping compensates radiation-induced hole trapping during positive gate-bias irradiation. Stress-induced hole trapping adds to the effects of radiation-induced hole trapping under negative gate bias. Radiation-induced charge trapping increases with the channel length.

Total Ionizing Dose Effects of Si Vertical Diffused MOSFET with SiO2 and Si3N4/SiO2 Gate Dielectrics

The total ionizing dose irradiation effects are investigated in Si vertical diffused MOSFETs (VDMOSs) with different gate dielectrics including single SiO2 layer and double Si3N4/SiO2 layer. Radiation-induced holes trapping is greater for single SiO2 layer than for double Si3N4/SiO2 layer. Dielectric oxidation temperature dependent TID effects are also studied. Holes trapping induced negative threshold voltage shift is smaller for SiO2 at lower oxidation temperature. Gate bias during irradiation leads to different VTH shift for different gate dielectrics. Single SiO2 layer shows the worst negative VTH at VG=0 V, while double Si3N4/SiO2 shows negative VTH shift at VG=-5 V, positive VTH shift at VG=10 V, and negligible VTH shift at VG=0 V.

Technology advancement of the CCD201-20 EMCCD for the WFIRST coronagraph instrument: sensor characterization and radiation damage

The Wide Field InfraRed Survey Telescope-Astrophysics Focused Telescope Asset (WFIRST-AFTA) mission is a 2.4-m class space telescope that will be used across a swath of astrophysical research domains. JPL will provide a high-contrast imaging coronagraph instrument - one of two major astronomical instruments. In order to achieve the low noise performance required to detect planets under extremely low flux conditions, the electron multiplying charge-coupled device (EMCCD) has been baselined for both of the coronagraph's sensors - the imaging camera and integral field spectrograph. JPL has established an EMCCD test laboratory in order to advance EMCCD maturity to technology readiness level-6. This plan incorporates full sensor characterization, including read noise, dark current, and clock-induced charge. In addition, by considering the unique challenges of the WFIRST space environment, degradation to the sensor's charge transfer efficiency will be assessed, as a result of damage from high-energy particles such as protons, electrons, and cosmic rays. Science-grade CCD201-20 EMCCDs have been irradiated to a proton fluence that reflects the projected WFIRST orbit. Performance degradation due to radiation displacement damage is reported, which is the first such study for a CCD201-20 that replicates the WFIRST conditions. In addition, techniques intended to identify and mitigate radiation-induced electron trapping, such as trap pumping, custom clocking, and thermal cycling, are discussed.

Characterization of Radiation Damage in Carbon Nanotube Field-Effect Transistors

<?Pub Dtl=""?> Carbon nanotube field-effect transistors with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm Al}_{2}{\rm O}_{3}$</tex></formula> gate dielectrics have been characterized before and after 1 MeV electron irradiation. Pre-irradiation interface trap densities determined by charge pumping measurements were on the order of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{11}~\hbox{cm}^{\hbox{-}2}\hbox{eV}^{\hbox{-}1}$</tex> </formula> . Following irradiation to fluences of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10^{16}~\hbox{e/cm}^2$</tex></formula> and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$10^{17}~\hbox{e/cm}^2$</tex></formula> , the measured interface trap densities decreased significantly for all devices. This result is largely attributed to the removal of molecular adsorbates that act as trap sites on the nanotubes (de-doping) while the devices are irradiated under vacuum. Negative shifts in the transistor <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I\hbox{-}V$</tex></formula> curves with irradiation indicate radiation-induced hole trapping in the gate dielectric, with some recovery after room temperature annealing. No significant changes were observed in the Raman spectra following irradiation, indicating the intrinsic structure of the carbon nanotubes remained unchanged. These results suggest that the radiation response of these devices is dominated by charge trapping in the oxide layers and at the carbon nanotube surfaces. Furthermore, the charge pumping technique can be used as a tool for probing surface adsorbates in carbon nanotube devices, and elucidating their role in the device radiation response.

Electrical Characterization of Gate Traps in FETs With Ge and III–V Channels

Many Ge and III-V-based MOSFETs, as well as GaN-based MOS-HEMTs, are significantly compromised in performance and reliability by their high densities of interface, border, and oxide traps. Problems may also arise when characterizing traps in FETs made on high-mobility channels due to their device structures and material properties that are different from their conventional counterparts. In this paper, we present the results of our study of these traps as obtained by the use of several electrical characterization techniques. In particular, we will discuss the ac transconductance technique that we have recently proposed, which enables us to probe interface traps in the band gap and border and bulk traps in the gate dielectrics even without a body contact. We will also show that the inelastic electron tunneling spectroscopy offers the unique possibility to use electrical characterization to understand chemical origins of traps without using additional physical characterization techniques. Ionizing radiation-induced trapping of charges in MOSFETs and MOS-HEMTs made on III-V semiconductors is also reported and discussed.

Global View on Dose Rate Effects in Silica-Based Fibers and Devices Damaged by Radiation-Induced Carrier Trapping

We give a novel and very general treatment to a standard model describing dose rate effects in systems damaged by carrier trapping. This model is well adapted for optical fibers, but the lessons we draw may also be helpful to discuss dose rate effects (DRE) in electronic devices. By highlighting the few determinant ratios of physical parameters that govern the system behavior, we clarify when, how and how much dose rate effects affect trap filling and radiation-induced degradation. Critical dose rate, marking the demarcation between low and high dose rate regimes, is also estimated as a function of these parameters. Taking this step back is important to enlighten contradictory results reported on DRE behaviors. The dose and dose rate dependencies of trap filling measured on silica optical fibers, as well as the critical dose rate, are successfully reproduced with a single set of a few adjustable physical parameters.

Wafer Level Statistical Evaluation of the Proton Radiation Hardness of a High-k Dielectric/Metal Gate 45 nm Bulk CMOS Technology

Although scaled down technologies may suffer from statistical parameter fluctuations caused by process variability, they are potentially radiation hard from a total-dose perspective. Therefore, the proton radiation hardness of a high-κ/metal gate 45 nm CMOS technology is studied using wafer level testing on 300 mm wafers. Attention is given to the correlation between pre- and post-radiation parameter variations. It is demonstrated that both the pre-irradiation process variability and the radiation-induced variability of the parameters have to be taken into account. For devices with a capping layer, the type of dielectric layer has an impact on the radiation-induced trapping mechanisms.

Impact of Back-Gate Bias and Device Geometry on the Total Ionizing Dose Response of 1-Transistor Floating Body RAMs

In this paper we investigate how geometry impacts the memory characteristics of 1-transistor dynamic floating body RAMs (FBRAMs) under total ionizing dose exposure. FBRAMs are implemented using fully depleted silicon-on-insulator devices with ultrathin buried oxide and body. Analytical models and experimental data are used to quantify the effects of charge trapping in the oxides and spacers on the memory read window shifts. The effects of increased radiation-induced leakage and interface trapping on the retention time are also discussed. Small geometry devices show reduced memory window shifts compared to large devices, but the retention time degradation is higher. The effects of coupling between interfaces and back-gate bias are also discussed in the context of memory characteristics.