scholarly journals A stochastic model of gamma-ray induced oxide charge distribution and threshold voltage shift of MOS transistors

2012 ◽  
Vol 27 (1) ◽  
pp. 33-39 ◽  
Author(s):  
Tijana Kevkic ◽  
Mihajlo Odalovic ◽  
Dragan Petkovic
Keyword(s):  
Stochastic Model ◽  
Silicon Dioxide ◽  
Charge Distribution ◽  
Threshold Voltage ◽  
Gamma Ray ◽  
Mos Transistors ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Silicon Dioxide Films ◽  
Induced Charge

A stochastic model of gamma-ray radiation effects on the density of the induced charge in silicon dioxide films of MOS transistors is presented in this paper. It is assumed that both radiation induced charge generation and trapped charge recombination are stochastic processes. For estimating gamma-ray induced charges spatially distributed in silicon dioxide films, a procedure similar to the Monte Carlo method was used. The proposed model implemented in the programming language MATHEMATICA enables us, for the first time, to show the gamma-ray induced charge distribution as a function of gamma-ray doses. Using the developed model, we have also calculated the corresponding threshold voltage shifts of MOS transistors. These results were compared with the experimentally determined threshold voltage shift of MOS transistors with different voltages applied during irradiation vs. gamma radiation doses. Satisfactory agreements were obtained.

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 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.

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.

Unusual Threshold Voltage Shift Caused by Self-Heating-Induced Charge Trapping Effect

2010 ◽  
Vol 13 (4) ◽  
pp. H95
Author(s):  
Fu-Yen Jian ◽  
Ting-Chang Chang ◽  
An-Kuo Chu ◽  
Te-Chih Chen ◽  
Shih-Ching Chen ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Charge Trapping ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Self Heating ◽  
Trapping Effect ◽  
Induced Charge

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%.

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