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 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.

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 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.

Threshold Voltage Shift in Hetero-nanocystal Floating Gate Flash Memory

2004 ◽  
Vol 832 ◽  
Author(s):  
Yan Zhu ◽  
Dengtao Zhao ◽  
Ruigang Li ◽  
Jianlin Liu
Keyword(s):  
Threshold Voltage ◽  
Flash Memory ◽  
Oxide Thickness ◽  
Memory Device ◽  
Floating Gate ◽  
Threshold Voltage Shift ◽  
Voltage Shift ◽  
Poisson Boltzmann ◽  
Poisson Boltzmann Equation ◽  
Dot Density

ABSTRACTThe threshold voltage shift of a p-channel Ge/Si hetero-nanocrystal floating gate memory device was investigated both numerically and phenomenologically. The numerical investigations, by solving 2-D Poisson-Boltzmann equation, show that the presence of the Ge on Si dot tremendously prolongs the retention time, reflected by the time decay behavior of the threshold voltage shift. The increase of the thickness of either Si or Ge dot will reduce the threshold voltage shift. The shift strongly depends on the dot density. Nevertheless, only a weak relation between the threshold voltage shift and the tunneling oxide thickness was found. A circuit model was then introduced to interpret the behavior of threshold voltage shift, which agrees well with the results of the numerical method.

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.

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