We have succeeded in utilizing In–Ga–Zn–O (IGZO) thin-film devices as synapse elements in a neural network. The electrical conductance is regarded as the connection strength, and the continuous change by flowing electrical current is employed as the connection plasticity based on the modified Hebbian learning as a learning rule. We developed a cellular neural network using the IGZO thin-film devices and confirmed that the neural network can learn simple logic functions. These results suggest a possibility to realize 3-D layered structure for brain-type integrated systems.
