Atomic step networks as selective epitaxial templates

A technique to control epitaxial growth laterally across a wafer is presented, which does not use a mask. A vicinal Si(111) substrate was patterned by optical lithography and heated to fabricate a regular pattern of bunches of atomic steps. Under appropriate growth conditions, it is seen that epitaxial material, here GaAs, sticks only to the step bunches, not to the terraces. It is possible to fabricate large-scale complex networks of GaAs with micron scale and submicron scale features. The conditions required to obtain selective growth are presented. It is shown that there are two regimes of selective growth—high temperature (>550 °C), or low temperature (<400 °C). Selectivity is obtained via two distinct mechanisms: desorption and diffusion, respectively.