Write mode circuitry for photovoltaic ferroelectric memory cell

Abstract

Non-volatile semiconductor matrix random access and electrically alterable rogrammable read-only memories are disclosed. Each memory cell of the matrix memory includes a photovoltaic ferroelectric element which is remanently polarized with a write signal, and which when illuminated, produces a photovoltage which causes a field effect transistor to assume one of two states. Variable impedance means, for example, at least a diode or a breakdown diode is connected in each cell for providing a low impedance when the write gate pulse is applied to the photovoltaic ferroelectric element and for providing a high impedance when the photovoltage produced by the photovoltaic ferroelectric element is applied to the field effect transistor gate. If power to the memory is lost, by illuminating the photovoltaic ferroelectric element, the field effect transistor may be caused to assume the state which it was in before loss of power.