  We have computationally demonstrated logic function implementations using
lateral and vertical multi-contact phase change devices integrated with CMOS
circuitry, which use thermal cross-talk as a coupling mechanism to implement
logic functions at smaller CMOS footprints. Thermal-crosstalk during the write
operations is utilized to recrystallize the previously amorphized regions to
achieve toggle operations. Amorphized regions formed between different pairs of
write contacts are utilized to isolate read contacts. Typical expected
reduction in CMOS footprint is ~ 50% using the described approach for
toggle-multiplexing, JK-multiplexing and 2x2 routing. The switching speeds of
the phase change devices are in the order of nanoseconds and are inherently
non-volatile. An electro-thermal modeling framework with dynamic materials
models are used to capture the device dynamics, and current and voltage
requirements.
