scholarly journals Sensitivity of P-Channel MOSFET to X- and Gamma-Ray Irradiation

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Milić Pejović ◽  
Olivera Ciraj-Bjelac ◽  
Milojko Kovačević ◽  
Zoran Rajović ◽  
Gvozden Ilić
Keyword(s):  
Threshold Voltage ◽  
Gamma Ray ◽  
Dose Range ◽  
Absorbed Dose ◽  
Tube Voltage ◽  
Threshold Voltage Shift ◽  
X Ray ◽  
Practical Applications ◽  
Most Significant Change ◽  
Gamma Ray Irradiation

Investigation of Al-gate p-channel MOSFETs sensitivity following irradiation using 200 and 280 kV X-ray beams as well as gamma-ray irradiation of 60Co in the dose range from 1 to 5 Gy was performed in this paper. The response followed on the basis of threshold voltage shift and was studied as a function of absorbed dose. It was shown that the most significant change in threshold voltage was in the case of MOSFET irradiation in X-ray fields of 200 kV and when the gate voltage was +5 V. For practical applications in dosimetry, the sensitivity of the investigated MOSFETs was also satisfactory for X-ray tube voltage of 280 kV and for gamma rays. Possible processes in gate oxide caused by radiation and its impact on the response of MOSFETs were also analyzed in this paper.

scholarly journals The effects induced by the gamma-ray responsible for the threshold voltage shift of commercial p-channel power VDMOSFET

2018 ◽  
Vol 33 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Marija Obrenovic ◽  
Milic Pejovic ◽  
Djordje Lazarevic ◽  
Nenad Kartalovic
Keyword(s):  
Radiation Dose ◽  
Threshold Voltage ◽  
Gamma Ray ◽  
Dose Range ◽  
Gate Bias ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Channel Power ◽  
Radiation Induced ◽  
Gamma Ray Irradiation

The variations in the threshold voltage shift in p-channel power VDMOSFET during the gamma ray irradiation was investigated in the dose range from 10 to 100 Gy. The investigations were performed without the gate bias and with 5 V gate bias. The devices with 5 V gate bias exhibit a linear dependence between the threshold voltage shift and the radiation dose. The densities of radiation-induced fixed and switching traps were determined from the sub-threshold I-V characteristics using the midgap technique. It was shown that the creation of fixed traps is dominant during the irradiation. The possible mechanisms responsible for the fixed and switching traps creation are also analyzed in this paper.

scholarly journals The gamma-ray irradiation sensitivity and dosimetric information instability of RADFET dosimeter

2013 ◽  
Vol 28 (4) ◽  
pp. 415-421 ◽  
Author(s):  
Milic Pejovic
Keyword(s):  
Threshold Voltage ◽  
Field Effect ◽  
Room Temperature ◽  
Gamma Ray ◽  
Field Effect Transistors ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Gamma Ray Irradiation

The gamma-ray irradiation sensitivity to radiation dose range from 0.5 Gy to 5 Gy and post-irradiation annealing at room and elevated temperatures have been studied for p-channel metal-oxide-semiconductor field effect transistors (also known as radiation sensitive field effect transistors or pMOS dosimeters) with gate oxide thicknesses of 400 nm and 1 mm. The gate biases during the irradiation were 0 and 5 V and 5 V during the annealing. The radiation and the post-irradiation sensitivity were followed by measuring the threshold voltage shift, which was determined by using transfer characteristics in saturation and reader circuit characteristics. The dependence of threshold voltage shift DVT on absorbed radiation dose D and annealing time was assessed. The results show that there is a linear dependence between DVT and D during irradiation, so that the sensitivity can be defined as DVT/D for the investigated dose interval. The annealing of irradiated metal-oxide-semiconductor field effect transistors at different temperatures ranging from room temperature up to 150?C was performed to monitor the dosimetric information loss. The results indicated that the dosimeters information is saved up to 600 hours at room temperature, whereas the annealing at 150?C leads to the complete loss of dosimetric information in the same period of time. The mechanisms responsible for the threshold voltage shift during the irradiation and the later annealing have been discussed also.

A Model of Gamma-Ray Irradiation Effects in Silicon Dioxide Films and on Silicon Dioxide - Silicon Interface

2007 ◽  
Vol 555 ◽  
pp. 147-152 ◽  
Author(s):  
M. Odalović ◽  
D. Petković
Keyword(s):  
Silicon Dioxide ◽  
Threshold Voltage ◽  
Gamma Ray ◽  
Monte Carlo Model ◽  
Mos Transistors ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Silicon Dioxide Films ◽  
Gamma Ray Irradiation ◽  
Silicon Interface

The gamma-ray irradiation causes positive charge traps formation in silicon dioxide films and at silicon dioxide - silicon interface of MOS devices, and the threshold voltage shift in MOS transistors. Here, the Monte Carlo model was used to develop an approach for estimating gammaray induced traps spatially distributed in silicon dioxide films. This is combined with the model of energy distributed traps at silicon dioxide - silicon interface. The developed model enables gammaray induced charge and threshold voltage shift determination as a function of gamma-ray doses. The threshold voltage measurements at a single specified current, both of radiation sensitive and radiation hardened MOS transistors irradiated with different doses of gamma-ray are compared with the developed model and good agreement are obtained.

scholarly journals Gamma-ray irradiation and post-irradiation at room and elevated temperature response of pMOS dosimeters with thick gate oxides

2011 ◽  
Vol 26 (3) ◽  
pp. 261-265 ◽  
Author(s):  
Momcilo Pejovic ◽  
Svetlana Pejovic ◽  
Edin Dolicanin ◽  
Djordje Lazarevic
Keyword(s):  
Elevated Temperature ◽  
Threshold Voltage ◽  
Gamma Ray ◽  
Temperature Response ◽  
Oxide Thickness ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Post Irradiation ◽  
Gamma Ray Irradiation ◽  
Oxide Traps

Gamma-ray irradiation and post-irradiation response at room and elevated temperature have been studied for radiation sensitive pMOS transistors with gate oxide thickness of 100 and 400 nm, respectively. Their response was followed based on the changes in the threshold voltage shift which was estimated on the basis of transfer characteristics in saturation. The presence of radiation-induced fixed oxide traps and switching traps - which lead to a change in the threshold voltage - was estimated from the sub-threshold I-V curves, using the midgap technique. It was shown that fixed oxide traps have a dominant influence on the change in the threshold voltage shift during gamma-ray irradiation and annealing.

scholarly journals Application of pMOS dosimeters in low-field mode for radiation dose measurements which could be used in radiotherapy

2016 ◽  
Vol 31 (4) ◽  
pp. 349-355 ◽  
Author(s):  
Svetlana Pejovic ◽  
Momcilo Pejovic ◽  
Dragan Stojanov
Keyword(s):  
Radiation Dose ◽  
Gamma Rays ◽  
Threshold Voltage ◽  
Dose Range ◽  
Field Mode ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
X Ray ◽  
Low Field ◽  
Absorbed Radiation Dose

The pMOS dosimeters sensitivity (Tyndall National Institute, Cork, Ireland) to gamma and X-ray irradiation and 2000 h fading at room temperature is presented. The radiation fields were created using a 60Co source for two dose ranges (1-5 Gy and 10-50 Gy) as well as for X-ray units of a 280 kV spectrum for a single dose range from 0.1 to 1 Gy. Irradiation was performed in low-field mode (no gate bias during irradiation, Virr = 0 V), sensitivity characterized by the threshold voltage shift as a function of the absorbed radiation dose and time after irradiation. Linear dependence between the threshold voltage shift and the absorbed radiation dose was only established for pMOS dosimeters which were irradiated by gamma rays in the dose range of 1 to 5 Gy. Obtained results show that the sensitivity of these components is much higher in case of X-ray radiation than in that of gamma ray radiation. Moreover, the fading of irradiated pMOS dosimeters with X-rays is higher than in the ones irradiated with gamma rays.

scholarly journals Sensitivity of RADFET for gamma and X-ray doses used in medicine

2014 ◽  
Vol 29 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Milic Pejovic ◽  
Svetlana Pejovic ◽  
Dragan Stojanov ◽  
Olivera Ciraj-Bjelac
Keyword(s):  
Radiation Dose ◽  
Gamma Radiation ◽  
Threshold Voltage ◽  
Linear Dependence ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Dose Range ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
X Ray

In this paper, the results of radiation sensitive field effect transistors (Al-gate p-channel metal-oxide-semiconductor field effect transistors) sensitivity to gamma and X-ray irradiation are presented. Radiation fields were created using 60Co source for three dose ranges (0-1 Gy, 0-5 Gy, and 0-50 Gy), as well as X-ray unit of 280 kVp spectrum for a single dose range from 0 to 5 Gy. The sensitivity was characterized by the threshold voltage shift, determined from reader circuit measurements, as a function of absorbed radiation dose. It was shown that for the three dose ranges of gamma radiation, as well as for the X-ray range from 0 Gy to 5 Gy there is approximately a linear dependence between threshold voltage shift DVT and radiation dose D. The application of positive bias of +5 V at the RADFET gate during irradiation, for these ranges of gamma radiation, also for X-ray dose range, leads to the increase in DVT and also, approximately a linear dependence between DVT and D, is established. Moreover, it was shown that the sensitivity of RADFET is much higher in the case of X-ray irradiation then in the case of gamma-ray irradiation for the same dose range.

scholarly journals Successive gamma-ray irradiation and corresponding post-irradiation annealing of pMOS dosimeters

2012 ◽  
Vol 27 (4) ◽  
pp. 341-345 ◽  
Author(s):  
Milic Pejovic ◽  
Momcilo Pejovic ◽  
Aleksandar Jaksic ◽  
Koviljka Stankovic ◽  
Slavoljub Markovic
Keyword(s):  
Threshold Voltage ◽  
Irradiation Dose ◽  
Elevated Temperatures ◽  
Gamma Ray ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Post Irradiation ◽  
Gamma Ray Irradiation ◽  
Value Changes ◽  
Dose Measurements

The paper investigates a possibility of pMOS dosimeter re-use for the measurement of gamma-ray irradiation. The dosimeters were irradiated to the dose of 35 Gy, annealed at room and elevated temperatures, after which they were irradiated again to the same dose value. Changes in the threshold voltage shift during those processes were followed, and it was shown that their re-use depends on a gate polarization during irradiation. For the gate polarization of 5 V during irradiation the pMOS dosimeters can be re-used for measurements of the irradiation dose after annealing without prior calibration. The pMOS dosimeters with the gate polarization during irradiation of 2.5 V can also be re-used for irradiation dose measurements but they require calibration. It is shown that for their re-use it is necessary to anneal the pMOS dosimeter so that the fading is higher than 50%.

scholarly journals Radiation-sensitive field effect transistor response to gamma-ray irradiation

2011 ◽  
Vol 26 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Milic Pejovic ◽  
Momcilo Pejovic ◽  
Aleksandar Jaksic
Keyword(s):  
Threshold Voltage ◽  
Gamma Ray ◽  
Interface Traps ◽  
Gate Bias ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Transfer Characteristics ◽  
Radiation Induced ◽  
Gamma Ray Irradiation ◽  
Oxide Traps

The influence of gate bias during gamma-ray irradiation on the threshold voltage shift of radiation sensitive p-channel MOSFETs determined on the basis of transfer characteristics in saturation has been investigated. It has been shown that for the gate bias during the irradiation of 5 V and 10 V the sensitivity of these transistors can be presented as the threshold voltage shift and the absorbed irradiation dose ratio. On the bases of the subthreshold characteristics and transfer characteristics in saturation using the midgap technique we have determined the densities of radiation induced oxide traps and interface traps responsible for the threshold voltage shift. In addition, the charge pumping technique was used to determine the energy density of true interface traps. It has been shown that radiation-induced oxide traps have dominant role on threshold voltage shift, especially for gate biases during the irradiation of 5 V and 10 V.

Calculation of the radiation dose absorbed by human biological tissue when using imaging equipment in radiоtherapy

2021 ◽  
pp. 56-59
Author(s):  
Irina M. Lebedenko ◽  
Sergej S. Khromov ◽  
Taras V. Bondarenko ◽  
Evgenij M. Chertenkov
Keyword(s):  
Monte Carlo ◽  
Radiation Therapy ◽  
Biological Tissue ◽  
Electron Accelerator ◽  
Absorbed Dose ◽  
Tube Voltage ◽  
X Ray ◽  
The Monte Carlo Method ◽  
Therapeutic Procedures ◽  
Dose Control

Considered the issues of X-ray dose control during diagnostic and therapeutic procedures using imaging tools. The dose of X-ray radiation from the visualization devices absorbed by the biological tissue of a person was determined when monitoring the position of the patient on the therapeutic table of the electron accelerator before the radiation therapy session. The processes of transmission of photons and electrons through the medium were simulated, and the X-ray spectra were measured. The emission spectrum of the Varian G-242 Rotating Anode X-ray Tube was obtained using an XR-100-CdTe spectrometer. The absorbed dose is calculated by the Monte Carlo method. The absorbed dose in the water phantom at tube voltage up to 80 kV was 0,9–1,5 mGy.

scholarly journals Negative threshold voltage shift in an a-IGZO thin film transistor under X-ray irradiation

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20865-20870 ◽  
Author(s):  
Dong-Gyu Kim ◽  
Jong-Un Kim ◽  
Jun-Sun Lee ◽  
Kwon-Shik Park ◽  
Youn-Gyoung Chang ◽  
...  
Keyword(s):  
Thin Film ◽  
Threshold Voltage ◽  
Thin Film Transistor ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Hydrogen Incorporation ◽  
X Ray ◽  
Spectroscopic Analyses ◽  
Bottom Gate ◽  
Igzo Tft

We studied the effect of X-ray irradiation on the negative threshold voltage shift of bottom-gate a-IGZO TFT. Based on spectroscopic analyses, we found that this behavior was caused by hydrogen incorporation and oxygen vacancy ionization.

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