Effects of packing materials on the sensitivity of RadFET with HfO₂ gate dielectric for electron and photon sources

Abstract

The radiation sensing field effect transistor (RadFET) with SiO₂ gate oxide has been commonly used as a device component or dosimetry system in the radiation applications such as space research, radiotherapy, and high-energy physics experiments. However, alternative gate oxides and more suitable packaging materials are still demanded for these dosimeters. HfO₂ is one of the most attractive gate oxide materials that are currently under investigation by many researchers. In this study, Monte Carlo simulations of the average deposited energy in RadFET dosimetry systems with different package lid materials for point electron and photon sources were performed with the aim of evaluating the effects of package lids on the sensitivity of the RadFET by using HfO₂ as a gate dielectric material. The RadFET geometry was defined in a PENGEOM package and electron–photon transport was simulated by a PENELOPE code. The relatively higher average deposited energies in the sensitive region (HfO₂ layer) for electron energies of 250 keV–20 MeV were obtained from the RadFET with the Al₂O₃ package lid despite of some deviations from the general tendency. For the photon energies of 20–100 keV, the average amount of energy deposited in RadFET with Al₂O₃ package was higher compared with the other capped devices. The average deposited energy in the sensitive region was quite close to each other at 200 keV for both capped and uncapped devices. The difference in the average deposited energy of the RadFET with different package lid materials was not high for photon energies of 200–1200 keV. The increase in the average deposited energy in the HfO₂ layer of the RadFET with Ta package lid was higher compared with the other device configurations above 3 MeV.

Keywords:

• RadFET
• HfO₂
• Monte Carlo
• package lid
• deposited energy
• dosimetry system

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work is supported by The Scientific and Technological Research Council of Turkey Science Fellowships and Grant Programs Department [TUBITAK-BIDEB 2218], TUBITAK 1002 Short Term R&D Funding Program [contract number 114F260]; the Ministry of Development of Turkey [contract number 2012K120360]; Abant Izzet Baysal University [contract number AIBU, BAP.2014.03.02.705].