A crystallization seed layer in a substrate, a phase change material layer, the phase change material layer includes a similar lattice constant as a lattice constant of the crystallization seed layer, a top electrode adjacent to a first vertical side surface and a bottom electrode adjacent to a second vertical side surface of the phase change material layer. A plurality of memory structures configured in a crossbar array, each including a crystallization seed layer, a phase change material layer above, a top electrode adjacent to a first vertical side surface and a bottom electrode adjacent to a second vertical side surface of the phase change material layer. A method including forming a crystallization seed layer, forming a phase change material layer, forming a top electrode and a bottom electrode on the substrate, each adjacent to a vertical side surface of the phase change material layer.