Pore Sealing on Si(001) and Si(111) in Homoepitaxy and Annealing: A Monte Carlo Simulation

A Monte Carlo simulation is reported of (i) the homoepitaxial growth of a continuous film on porous Si(111) and Si(001) surfaces and (ii) high-temperature annealing of a porous-silicon substrate. The simulation is based on a 3D model for diamond-type crystals. It is shown that homoepitaxy produces a smooth film on a (111) surface, whereas the film on a (001) surface shows {111} tetrahedral pits. It is found that the minimum deposited dose required for pore sealing is much lower for a (111) surface; this is true of all temperatures, deposition rates, and porosities considered. The difference in surface morphology between the two films is attributed to the influence of surface orientation on adatom migration. The variation is examined of pore penetration depth with respect to epitaxy conditions and porosity. Structural changes under annealing are investigated in the Si(001) case.