TWO-TERMINAL SWITCHING DEVICES AND THEIR METHODS OF FABRICATION
Two-terminal switching devices characterized by high on/off current ratios and by high breakdown voltage are provided. These devices can be employed as switches in the driving circuits of active matrix displays, e.g., in electrophoretic, rotating element and liquid crystal displays. The switching devices include two electrodes, and a layer of a broad band semiconducting material residing between the electrodes. According to one example, the cathode comprises a metal having a low work function, the anode comprises an organic material having a p+ or p++ type of conductivity, and the broad band semiconductor comprises a metal oxide. The work function difference between the cathode and the anode material is preferably at least about 0.6 eV. The on/off current ratios of at least 10,000 over a voltage range of about 15 V can be achieved. The devices can be formed, if desired, on flexible polymeric substrates having low melting points.
1 . An electronic device comprising:
a substrate;
a plurality of two-terminal devices disposed on the substrate, wherein each two-terminal device comprises:
a first electrode comprising a layer of first conductive material, having a first work function;
a layer of a broad band semiconducting material physically separate from the layers of semiconducting material on other of the two-terminal switching devices, wherein the band gap of the broad band semiconductor is at least about 2.5 eV and the carrier concentration in the broad band semiconductor is less than about 10 18 cm −3 ; and
a second electrode comprising a layer of a second conductive material, having a second work function, wherein the second conductive material comprises a material having a p+ or p++ type conductivity; wherein
at least a portion of the semiconductor layer resides between the first and second conductive materials, wherein the second work function magnitude is greater than the first work function magnitude.