Study on polysilicon extended gate field effect transistor with samarium oxide sensing membrane

The first material of silicon dioxide (SiO
₂
) had been proposed as a chemical transducer element of pH sensitive membrane around the early of 1970s. In 1981 Matsuo et al. proposed Ta
₂
O
₅
as pH sensing membrane. Start from that moment, many materials have been wildly investigated, e.g. Al
₂
O
₃
, SnO
₂
, WO
₃
. The rare -earth oxide, Samarium oxide (Sm
₂
O
₃
), is an attractive material to substitute the previous high-k materials because of its high dielectric constant(15-30) and good chemical and thermal stability with Si material. In this paper, the electrical and physical characteristics of the high-k Sm
₂
O
₃
polyoxides by RF sputtering system deposited on the polycrystalline silicon were studied. It can be seen that the high-k Sm
₂
O
₃
polyoxides with post rapid thermal annealing (RTA) can show lower trapping rates and higher dielectric breakdown fields. Furthermore, the EGFET device with a high-k Sm
₂
O
₃
sensing membrane deposited on polysilicon through reactive sputtering was proposed for high sensitive pH sensing.