Topological defects of blue-phase liquid crystals (BPLCs) can be self-assembled into three-dimensional cubic crystalline structures, representing unique ordered states of matter among other liquid crystals. In a recent study, we presented the preparation of stable, macroscopic single-crystal blue phase materials by using chemically-patterned surfaces with binary anchoring and the appropriate geometry to favor a desired crystallographic orientation of the BPLC. Here we study the thickness dependence for chemically patterned surface for the crystal growth of the blue-phase II –which is characterized by a simple cubic crystalline structure, under a thermally controlled process. The hybrid cell used in our work to direct the self-assembly of the BP LCs has a top surface that provides uniform homeotropic anchoring, and a bottom surface with chemical patterns consisting of a stripe array of alternative planar and homeotropic anchoring. There is a spacer in between the two substrates to vary the cell thickness. Under such a process we achieve single crystals of blue-phase II with a -lattice orientation (BPII) that start to nuclei and grow from the pattern surface and propagate through the cell. By changing the cell thickness, we analyze the morphology difference of crystalline BPII on the pattern surface.