Proposal of dual-gate oxide layered with HfO2: Comparative results with SiO2-RadFET

Abstract

The aim of this study is to develop pMOS dosimeters that can exhibit high performance at high radiation doses compared to traditional SiO₂-based RadFETs, for which a dual-gate oxide-layered sensor is proposed. The sensor chips, consisting of two RadFETs of identical thickness and geometry, were fabricated with sensitive region materials of 100 nm and 300 nm thick SiO₂, as well as 40 nm HfO₂/5 nm SiO₂. The threshold voltages ($V_{th}$) of the sensors were determined based on voltage values corresponding to 10 μA ve 50 μA currents. The initial $V_{th}$ values at 10 μA/50 μA of the RadFETs were −2.89 ± 0.01 V/−3.84 ± 0.01 V for 100 nm SiO₂, -4.37 ± 0.02 V/-6.02 ± 0.02 for 300 nm SiO₂, and -1.04±<%0.08 V/-1.507 ± 0.002 V for HfO₂/SiO₂. RadFETs were irradiated under a⁶⁰Co radioactive source within a dose range of 1–20 Gy. The sensitivities of the sensors for a cumulative dose of 20 Gy were calculated as 9.19 ± 0.21/9.81 ± 0.19 mV/Gy for 100 nm-SiO₂-RadFET, 43.72 ± 0.80/45.94 ± 0.68 mV/Gy for 100 nm-SiO₂-RadFET, and 0.83 ± 0.01/0.87 ± 0.02 mV/Gy for DGHK-RadFETs (dual-gate oxide layered with high-k), based on data obtained at 10/50 μA, respectively. No degradation was observed in any of the sensors during the studied dose range, and the DGHK-RadFETs demonstrated particularly stable behavior. Lower error rates in performance parameters, higher stability, more durable in high radiation environments, greater dose storage capability with the lowest fading values, and the ability to reach saturation at higher doses were observed in DGHK-RadFETs compared to SiO₂-RadFETs. All these superior properties compared to traditional structures have been achieved in DGHK-RadFETs with a thinner sensitive region. The DGHK-RadFET prototype is a promising candidate for potential applications in nuclear power plants, space research, high-energy physics laboratories, and defense and security applications.