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 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 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.

Negative threshold voltage shift for LTPS TFTs under x-ray irradiation and gate bias

2019 ◽  
Vol 34 (9) ◽  
pp. 095012 ◽  
Author(s):  
Ya-Hsiang Tai ◽  
Shan Yeh ◽  
Po-Chun Chan ◽  
Yi-Shen Li ◽  
Shih-Hsuan Huang ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Gate Bias ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
X Ray

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 Analysis of Threshold Voltage Shift for Full VGS/VDS/Oxygen-Content Span under Positive Bias Stress in Bottom-Gate Amorphous InGaZnO Thin-Film Transistors

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 327
Author(s):  
Je-Hyuk Kim ◽  
Jun Tae Jang ◽  
Jong-Ho Bae ◽  
Sung-Jin Choi ◽  
Dong Myong Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Electric Field ◽  
Oxygen Content ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Electron Trapping ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Drain Side ◽  
Bottom Gate

In this study, we analyzed the threshold voltage shift characteristics of bottom-gate amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) under a wide range of positive stress voltages. We investigated four mechanisms: electron trapping at the gate insulator layer by a vertical electric field, electron trapping at the drain-side GI layer by hot-carrier injection, hole trapping at the source-side etch-stop layer by impact ionization, and donor-like state creation in the drain-side IGZO layer by a lateral electric field. To accurately analyze each mechanism, the local threshold voltages of the source and drain sides were measured by forward and reverse read-out. By using contour maps of the threshold voltage shift, we investigated which mechanism was dominant in various gate and drain stress voltage pairs. In addition, we investigated the effect of the oxygen content of the IGZO layer on the positive stress-induced threshold voltage shift. For oxygen-rich devices and oxygen-poor devices, the threshold voltage shift as well as the change in the density of states were analyzed.

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