Adaptive-learning neuron integrated circuits using metal-ferroelectric (SrBi2Ta2O9)-semiconductor (MFS) FET's

An adaptive-learning neuron circuit was fabricated for the first time by in tegrating a metal-ferroelectric-semiconductor (MFS) FET and a complementary unijunction transistor (CUJT) on a silicon-on-insulator (SOI) structure. S rBi2Ta2O9 (SBT) was selected as a ferroelectric gate material and it was de posited by liquid source misted chemical deposition (LSMCD) method. In fabr ication of the circuit, a new selective etchant, NH4F:HCl, was used to remo ve the unnecessary SET film, since it was found from preliminary experiment s that the parasitic ferroelectric capacitors prevented normal operation of the circuit. It was found that the drain current of MFSFET was changed gra dually by applying a number of input pulses with a sufficiently short durat ion time of 20 ns, The gradual change in the output pulse frequency of the neuron circuit was also demonstrated as the number of input pulses was incr eased.