To study the effect of a charged substrate on the crystallization, we included a negatively charged wall at position Z min in the simulation box. The charged wall is formed of a hexagonal arrangement of spherical particles of radius 30 nm. The interaction between the charged wall and a colloid particle was modeled using the same combined DLVO+brush potential as between the two primary species. The surface potential of the wall particles was varied from -45 mV to -50 mV.