Neuromorphic Applications of a Multivalued [SnI₄{(C₆H₅)₂SO}₂] Memristor Incorporated in the Echo State Machine

The operation of an FTO/[SnI4{(C6H5)2SO}2]/Cu memristor is based on the Schottky barrier modulation due to electron trapping/detrapping at the interface states. The presented memristive bipolar device has an asymmetric current–voltage characteristic and multiple resistance states, which can be achieved by the application of impulses with different amplitudes and durations. STDP measurement performed with symmetric sawtooth voltage pulses results in the asymmetric Hebbian-like learning pattern. The incorporation of the device in a particular type of the reservoir system—a single node echo state machine—allowed observation of signal processing in a feedback-loop equipped system: classification according to the initial pulse amplitude and generation of pulse sequences of a random length.