Two types of hybrid CMOS-molecular memories with large scaling potential are discussed; resistive memories based on functional molecular layers and charge trapping devices with integrated nanotubes. For the first type, the resistive memory, crossbar cell and transistor cell architectures are compared. In the crossbar geometry the advantage of a dense cell geometry comes at the cost of more complex circuitry and complicated process technology, whereas the transistor cell has, in general, a lower area density, but enhanced read-write performance and reduced disturbance. However, using a specially designed vertical transistor architecture a cell size similar to that in the crossbar cell can be realized. The other concept for a highly scalable non-volatile memory is based on the integration of nanowires or nanotubes into standard silicon technology. In this memory cell, charges in the trapping layer shift the threshold voltages of nanotube-based transistors, while controlling and readout can be done by conventional CMOS electronics.
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