Semiconductor device

Claim 1

In a non-volatile memory device comprising at least two layers of different conductivity type selected from i-, p- and n-type amorphous or micro-crystalline semi-conductor and which exhibitsd across said layers at least two stable conductance state of high and low conductance respectively at an applied voltage between given positive threshold voltages and which is repeatedly switchable between said conductance states by applied voltage of opposite polarity which device is produced by applying a forming voltage to a layered structure which does not have non-voltatide memory properties the improvement which comprises providing an additional d-type layer of amorphous or micro-crystalline semi-conductor located between two or said different layers and in contact with two of said layers, said d-type layer having an average thickness not exceeding 12 Angstroms, and having pooere electronic properties than the other semi-conducting layers such that it has a substantially smaller increase in conductivity on illumination under standard AM 1.5 conditions than the material of any other layer of the same semi-conductor forming part of the p-, n-or i-layers of the device, and such that the forming voltage of the device is not more than 60% of the forming voltage of an otherwise identical device without the d-layer.