Irradiation response of radio-frequency sputtered Al/Gd2O3/p-Si MOS capacitors.

The usage of the Gadolinium oxide (Gd 2 O 3 ) as sensitive region in the MOS (Metal-Oxide-Semiconductor)-based dosimeters was investigated in the presented study. The Gd 2 O 3 films grown on p-type Si (100) by RF magnetron sputtering were annealed at 800 °C under N 2 ambient. The back and front metal contacts were establishes to produce MOS capacitors. The fabricated Gd 2 O 3 MOS capacitors were irradiated in the dose range 0.5–50 Gy by 60 Co gamma source. The performed Capacitance-Voltage (C-V) curves of the Gd 2 O 3 MOS capacitors shifted to right side relative to pre-irradiation one. While continuous increments in the oxide trapped charges with increasing in gamma dose were observed, interface trapped charges fluctuated in the studied dose range. However, the variation of the interface trapped charge densities was found in the order of 10 11 cm −2 and no significant variation was observed with applied dose. These results confirm that a significant deterioration does not occur in the capacitance during the irradiation. The higher oxide trapped charges compared to interface trapped charges showed that these traps were more responsible for the shift of the C-V curves. The sensitivity and percentage fading after 105 min of the Gd 2 O 3 MOS capacitor were found as 39.7±1.4 mV/Gy and ~14.5%, respectively. The devices sensitivity was found to be higher than that of capacitors composed of Er 2 O 3 , Sm 2 O 3 , La 2 O 3 , Al 2 O 3 , and SiO 2 , but, the high fading values is seen as a major problem for these capacitors. Finally, the barrier height was investigated with gamma exposure and the results showed that its value increased with increasing in radiation dose due to possible presence of the acceptor-like interface states. [ABSTRACT FROM AUTHOR]