Effects Of Total Dose Irradiation Research Articles

Effect of Total Dose Irradiation on Parasitic BJT in 130 nm PDSOI MOSFETs.

In this work, the effects of total dose irradiation on the parasitic bipolar junction transistor (BTJ) in 130 nm PDSOI MOSFETs were investigated. The experimental results demonstrate that irradiation-induced oxide-trap charges can modify the E-B junction barrier, and thereby make the common-emitter gain β0 of the parasitic BJT in NMOS device increase, while decreasing it in a PMOS device. Additionally, irradiation-generated oxide-trap charges in shallow trench isolation (STI) elevate the surface electrostatic potential of the gate above the STI sidewall, thus providing an additional channel from the emitter to the collector. Moreover, these charges may generate parasitic reverse conductive paths at the STI/Si interface under high dose irradiation, thereby enhancing the leakage current in the front gate channel and diminishing the significance of the parasitic BJT. Under irradiation, the electric field intensity difference between two biases leads to higher β0 of the parasitic BJT in PG-biased devices than in ON-biased ones. Furthermore, the lifting effect of irradiation on β0 increases in wide or short channel irradiated devices, which can be explained using simulations and an emitter current crowding effect model.

Impact of γ -Ray Irradiation on Graphene-Based Hall Sensors

The effects of total dose irradiation on graphene-based Hall sensors were investigated by <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sup> Co γ-ray in this paper. The basic electrical parameters of the sensors were measured before and after γ-ray irradiation up to 1 Mrad(Si). Decreases in the Hall voltage, linearity and current-related sensitivity in response to γ-ray irradiation were observed. With the help of Raman spectroscopy and X-ray photoelectron spectra (XPS), the degradation after irradiation was attributed to the introduction of defects and the increase in doping concentrations in the graphene layer. Moreover, the introduction of defects and impurities enhanced the Coulomb scattering of carriers, resulting in a decrease in mobility, which in turn affected the sheet resistance. This work provides an insight into the interactions of ionizing irradiation with graphene-based Hall sensors, which could be applied in space or other irradiation sensitive applications.

Influence of gamma ray radiation on two-dimensional sub-threshold current of strained Si nano NMOSFET

ABSTRACTThe carrier transport in uniaxial strained Si N channel metalvn oxide semiconductor field effect transistor (NMOSFET) irradiated by gamma rays is analyzed. Based on the total dose irradiation effect, an analytical model of two-dimensional sub-threshold current for differential capacitance of uniaxial strained Si Nano NMOSFET is established. Based on this model, numerical calculation is carried out by MATLAB. The influence of geometric parameters and total dose on differential capacitance is simulated. Meanwhile, the simulation results match the experiment result very well, which validates the accuracy of the model. Therefore, the model provides a good reference for the irradiation reliability of uniaxial strained Si nano NMOSFET and the application of strained integrated circuits.

Total Dose Radiation Response of Capacitance Characteristic for Nano-scale NMOS

The carrier transport in uniaxial strained Si N channel metal oxide semiconductor field effect transistor (NMOSFET) irradiated by gamma rays is analysed. Based on the total dose irradiation effect, an analytical model for differential capacitance of uniaxial strained Si Nano NMOSFET is established. Based on this model, numerical calculation is carried out by MATLAB. The influence of geometric parameters and total dose on differential capacitance is simulated. Meanwhile, the simulation results match the calculation results very well, which validate the accuracy of the model. Therefore, the model provides a good reference for the irradiation reliability of uniaxial strained Si nano NMOSFET and the application of strained integrated circuits.

Influence of -ray total dose radiation effect on the tunneling gate current of the uniaxial strained Si nanometer n-channel metal-oxide-semiconductor field-effect transistor

The carrier microscopic transport process of uniaxial strained Si n-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) is analyzed under -ray radiation. The model of radiation-induced defect densities that are quantitative representations of trapped charges integrated across the thickness of the oxide (Not), and the number of interface traps at the semiconductor/oxide interface (Nit), is established. The variations of electrical characteristics of the uniaxial strained Si nanometer NMOSFET are also investigated under the total dose radiation. The device of uniaxial strained Si nanometer NMOSTET is irradiated by a 60Co -ray laboratory source at a constant dose rate of 0.5 Gy (Si)/s. The TID is deposited in several steps up to a maximum value of 2.5 kGy. Electrical measurements are performed at each TID step. All irradiated samples are measured using field test, and are required to finish measurement within 30 min, in order to reduce the annealing effect. Static drain-current ID vs. gate-voltage VGS electrical characteristics are measured with an HP4155B parametric analyzer. Some parameter extractions presented here come from these static measurements including the threshold voltage VTH, the trans-conductance gm, and the leakage current IOFF (ID at VGS=0 V and VDS=VDD). Irradiation bias:VG=+1 V, drain voltage VD is equal to source voltage VS (VD=VS=0). Measurement bias:VG=0-1 V, scanning voltage Vstep=0.05 V, VD=50 mV, and VS=0. The results indicate the drift of threshold voltage, the degradation of carrier mobility and the increase of leakage current because of the total dose radiation. Based on quantum mechanics, an analytical model of tunneling gate current of the uniaxial strained Si nanometer is developed due to the total dose irradiation effect. Based on this model, numerical simulation is carried out by Matlab. The influences of total dose, geometry and physics parameters on tunneling gate current are simulated. The simulation results show that when radiation dose and bias are constant, the tunneling gate current increases as the channel length decreases. When the structure parameters and the stress are fixed, the tunneling gate current increases with the increase of radiation dose. Whereas at a given the radiation dose, tunneling gate current will decrease due to the stress. When radiation dose and bias are kept unchanged, the tunneling gate current increases with the thickness of the gate oxide layer decresing. When the gate-source voltage, the thickness of oxide layer and stress are fixed, tunneling gate current is reduced with the increase of doping concentration in channel. When the structural parameters, the gate-source voltage and radiation dose are constant, the tunneling gate current decreases with increasing drain-source voltage. In addition, to evaluate the validity of the model, the simulation results are compared with experimental data, and good agreement is confirmed. Thus, the experimental results and proposed model provide good reference for research on irradiation reliability and application of strained integrated circuit of uniaxial strained Si nanometer n-channel metal-oxide-semiconductor field-effect transistor.

Effects of total dose irradiation on the threshold voltage of H-gate SOI NMOS devices

This work researched the impact of total dose irradiation on the threshold voltage of N-type metal oxide semiconductor field effect transistors (nMOSFETs) in silicon-on-insulator (SOI) technology. Using the subthreshold separation technology, the factor causing the threshold voltage shift was divided into two parts: trapped oxide charges and interface states, the effects of which are presented under irradiation. Furthermore, by analyzing the data, the threshold voltage shows a negative shift at first and then turns to positive shift when irradiation dose is lower. Additionally, the influence of the dose rate effects on threshold voltage is discussed. The research results show that the threshold voltage shift is more significant in low dose rate conditions, even for a low dose of 100 krad(Si). The degeneration value of threshold voltage is 23.4 % and 58.0 % for the front-gate and the back-gate at the low dose rate, respectively.

Total dose dependence of hot carrier injection effect in the n-channel metal oxide semiconductor devices

The equipment and devices which are long-time running in space are affected by space radiation effects and hot carrier injection effects at the same time which would reduce their optional times. Normally, the single mechanism test simulation method is used on the ground simulation test but the multi-mechanism effect affects the space equipments and devices, including total irradiation dose effect, hot carrier injection effect, etc. The total dose dependence of hot carrier injection (HCI) effect in the 0.35 m n-channel metal oxide. semiconductor (NMOS) device is studied in this paper. Three samples are tested under different conditions (sample 1# with total irradiation dose (TID) and HCI test, sample 2# with TID, annealing and HCI test, sample 3# only with HCI test). The results show that threshold voltage of NMOS device with 5000 s HCI test after 100 krad (Si) total dose radiation has been negatively shifted then positively during total dose irradiation test and HCI test, and the threshold is higher than that of the device without radiation test. But the threshold voltage shift of NMOS device with 5000 s HCI test and 200 h annealing test after TID test is higher than that of the devices without radiation test and lower than that of the devices without annealing test. That is, the parameters of NMOS device vary faster with the combined effects (including the total dose irradiation effect and HCI effect) than with single mechanism effect. It is indicated that the hot electrons are trapped by the oxide trap charges induced by irradiation effect and then become a recombination centre. And then the oxide trap charges induced by irradiation effect reduce and become negative electronic. The interface trap charges induced by irradiation effect are reduced and then increased it is because the electrons of hole-electron pairs in the Si-SiO2 interface are recombined by oxide traps in the oxide during the forepart of HCI test but then the electrons are trapped by interface traps in the Si-SiO2 interface because the electrons from source area are injected to interface during the HCI test. So the threshold voltage is positively shifted due to the negative oxide trap charges and interface trap charges. The association effect is attributed to the reduction of oxide traps induced by recombination with hot electrons and the increase of the interface traps induced by irradiation trapped hot electrons.

Influence of channel length on PD SOI PMOS devices under total dose irradiation

This paper mainly investigates the total dose irradiation effects on 0.8 μm PD SOI PMOS devices which are exposed to 60Co γ-rays at a dose rate of 50 rad(Si)/s. The channel length dependence of SOI PMOS devices at total dose irradiation is investigated. The result shows that the threshold voltage shift is only a little larger for shorter channel devices at the same total dose. However, the degradation of maximum transconductance for shorter channel devices is more significant. We found that the oxide-trapped charge is the main factor impacting the threshold drift. We may conclude that a short channel device can produce more interface trapped charges by using the subthreshold separation technology.

Total dose irradiation and hot-carrier effects of sub-micro NMOSFETs

Total dose irradiation and the hot-carrier effects of sub-micro NMOSFETs are studied. The results show that the manifestations of damage caused by these two effects are quite different, though the principles of damage formation are somewhat similar. For the total dose irradiation effect, the most notable damage lies in the great increase of the off-state leakage current. As to the hot-carrier effect, most changes come from the decrease of the output characteristics curves as well as the decrease of trans-conductance. It is considered that the oxide-trapped and interface-trapped charges related to STI increase the current during irradiation, while the negative charges generated in the gate oxide, as well as the interface-trapped charges at the gate interface, cause the degradation of the hot-carrier effect. Different aspects should be considered when the device is generally hardened against these two effects.

The total dose irradiation effects of SOI NMOS devices under different bias conditions

Based on 0.8 μm process, in the paper we investigate the total dose irradiation effects of SOI NMOS devices under different bias conditions. The devices are exposed to 60Co γ ray at a dose rate of 50 rad (Si)/s. In higher gate bias condition, the drain leakage current increases because more positive charges are trapped in the buried oxide. When the applied gate voltage is larger than the threshold voltage, its drain current of the front gate in ID-VG characteristic suddenly increases and the body current presents a unique upside down bell shape.

Research on the total-dose irradiation damage effect for static random access memory-based field programmable gate array

In order to investigate the total-dose irradiation effects of Altera static random access memory (SRAM)-based FPGA (field programmable gate array), the irradiation response of basic cell of FPGA, i.e. the CMOS, is studied, and the relationship of the output waveform as a function of total dose has been obtained. It indicates that the output waveforms become aberrated and the peak-peak value turns to about 1/10 of the initial value as the total dose increased, resulting from the degradation of leakage current both from field oxygen and the structure; but there are relatively high and low levels left in the output waveforms. Meanwhile, the high level cant keep the already existing state and changes to the low level, and the conversion speed is accelerated with the increase of the total dose. The low level becomes larger than the initial value. As the gate-oxygen is quite thin, the rise time, fall time, and delay of the output waveforms change little with the total dose.

Pseudo-Mosfet Analysis of Proton Irradiated and Annealed SOI Wafer

The total dose irradiation effect on the SOI wafer is analyzed at the material level by pseudo-MOSFET technique. The proton irradiation induces positively charged traps in the buried oxide (BOX) and amphoterically charged traps at the film-BOX interface. The amphoteric interface trap charges contribute to the shift in threshold and flatband voltages by accentuating or attenuating the effect of the positive fixed charge in the BOX. The inherent ambipolar pseudo-MOSFET characteristics reveal both NMOS and PMOS properties, making it possible to identify and separate the charges that contribute to the shift of the turn-on voltage. The negatively charged acceptor-like states are located in the upper part of bandgap whereas the positively charged donor-like states are situated in the lower part of bandgap. These interface trap states can be removed by low-temperature annealing, so that only the oxide trapped charges continue to govern the turn-on voltage shift.

Investigation on a solution to improve the irradiation reliability of SOI NMOSFET

A solution is developed to improve the irradiation reliability of SOI NMOSFET (N-type Metal Oxide Semiconductor Field Effect Transistor). This solution, including SOI (Silicon On Insulator) wafer hardening and transistor structure hardening, protects the SOI circuit from total dose irradiation effect.

Effects of total-dose irradiation on gate-all-around (GAA) devices

The response of gate-all-around (GAA) MOS transistors to dose irradiation is quite different from that observed on other types of silicon-on-insulator (SOI) MOSFETs. In regular SOI MOSFETs, edge leakage increases substantially faster than the main transistor leakage upon creation of oxide charges due to the irradiation. The GAA MOSFET behaves in the opposite way; the shift of edge threshold voltage upon creation of charges in the oxide is smaller than that of the main transistor. As a result, a kink develops in the subthreshold characteristics of regular SOI MOSFETs upon irradiation, while the original subthreshold kink of GAA devices disappears when the device is irradiated. >

Characteristics of the Breakdown Voltage of Power MOSFETs after Total Dose Irradiation

The effects of total dose irradiation on the breakdown voltage of p-channel power MOSFETs are examined. Although breakdown voltage for p-channel devices increased at higher dose levels, as expected, some devices exhibited an initial decrease in breakdown at very low levels of total dose. The interaction of ionizing radiation effects with the junction termination methods designed to increase the voltage at which breakdown occurs is analyzed.