The contribution of border traps to the threshold voltage shift in pMOS dosimetric transistors

Abstract

Abstruct-The instability of PMOS dosimetric transistors inThe dosimetric PMOS transistors, also called RADFET's, the form of threshold voltage drift could be an important source of errors in low dose measurements. The source of the drift is, according to the recent nomenclature, switching states concerned with near-interfacial oxide traps (border traps), and we have investigated them for 10 different types of specially prepared PMOS transistors. It has been found that the density of these states depends on the received dose, the bias during irradiation, the temperature, and the thickness of the gate oxide and its hydrogen content. A tunneling model that successfully describes the threshold voltage drift and explains these experimental results is presented. The possible physical picture of border traps and two specific structural models of defects in the Si02 which could be concerned with these experimental results are also discussed.

The empirical dependence of radiation-induced charge neutralization on negative bias in dosimeters based on the metal-oxide-semiconductor field-effect transistor

“…This provides a more stable measurement of the threshold voltage since the short-term drift due to border traps 21 is reduced. 22 The MOSFET dosimeters have been irradiated within a polymethylmethacrylate ͑PMMA͒ phantom to ensure charge equilibrium in the vicinity of the MOSFET and uniform radiation dose. The dimensions of the phantom were 300 ϫ 300ϫ 200 mm.…”

Application of p-Channel Power VDMOSFET as a High Radiation Doses Sensor

“…Sensitivity can be controlled by the gate bias during irradiation. It was shown [33], [34] that sensitivity increases with gate voltage increase during irradiation and that it is higher in the case of positive gate bias, then negative gate bias (the lowest sensitivity is for zero gate bias). Furthermore, an increase in sensitivity can also be achieved with the increase in gate oxide layer thickness [35] and by processing conditions, which determine the FT density, their capture cross section and their location as well as the interface traps density [36].…”

Influence of Ionizing Radiation and Hot Carrier Injection on Metal-Oxide-Semiconductor Transistors

“…at the start of annealing. The papers [136][137][138][139][140][141][142][143] show the results of exposure to gamma radiation and subsequent annealing of PMOS dosimetric transistors manufactured in the company EiMicroelectronics, Nis, Serbia, while the papers [135,[143][144][145] show the results of radiation and annealing of PMOS dosimetric transistors manufactured in Tyndall National Institute, Cork, Ireland. Figure 27 shows change in threshold voltage with an increase in absorbed dose of gamma radiation for the transistors with oxide thickness of 1.23 µm [136].…”