Methods and associated apparatus of forming a microelectronic structure are described. Those methods comprise providing a substrate comprising a region of higher active area density comprising source and drain recesses and a region of lower active area density comprising source and drain recesses, wherein the region of lower active area density further comprises dummy recesses, and selectively depositing a silicon alloy layer in the source, drain and dummy recesses to enhance the selectivity and uniformity of the silicon alloy deposition.