Thermally induced morphology evolution of pit-patterned Si substrate and its effect on nucleation properties of Ge dots

We demonstrate the effect of the pre-growth heat treatment process on the nucleation properties of Ge dots grown on pit-patterned Si(001) substrates. The prefabricated 200 nm diameter pits inherently evolve into truncated inverted pyramids (TIPs) with 110 base edges and a 7°–9° sidewall slope during heat treatment; this morphology transformation is robust against variations in shape and orientation of the pit patterns. Uniform Ge dots with an areal density of 4 × 109 cm − 2 were obtained on the Si substrates having TIPs. Each TIP contains four aligned Ge dots locating symmetrically with respect to 110. These dots exhibit an elliptical dome shape with major axis oriented along 100. The nucleation position, shape and spatial orientation of these Ge dots coincide with the calculated surface chemical potential distribution of the TIP.