  We propose energy bandpass filtering employed using the idea of
anti-reflection heterostructures as a means to reduce the energy requirements
of a superlattice phase change memory based on GeTe and Sb$_{2}$Te$_{3}$
heterostructures. Different configurations of GeTe/Sb$_{2}$Te$_{3}$
superlattices are studied using the non-equilibrium Green's function approach.
Our electronic transport simulations calculate the coupling parameter for the
high resistance covalent state, to $97 \%$ that of the stable low resistance
resonant state, maintaining the ON/OFF ratio of 100 for a reliable read
operation. By examining various configurations of the superlattice structures
we conclude that the inclusion of anti-reflection units on both sides of the
superlattice increases the overall ON/OFF ratio by an order of magnitude which
can further help in scaling down of the memory device. It is also observed that
the device with such anti-reflection units exhibits 32$\%$ lesser RESET voltage
than the most common PCM superlattice configurations and 27$\%$ in the presence
of elastic dephasing. Moreover, we also find that the ON/OFF ratios in these
devices are also resilient to the variations in the periodicity of the
superlattice.
