Macropores in p-Type Silicon

Though macropore growth on p-Si has appeared years after the corresponding studies started on n-Si, it seems to have reached a fair level of control and understanding. In general, crystallographic effects appear somewhat less marked for p-Si than for n-Si. However, strongly anisotropic pore growth may be obtained in suitable non-aqueous solvents. Although macropores, in p-Si as well as in n-Si, do not exhibit spontaneous long-range ordering, they can be grown as long-range ordered arrays if the growth is initiated by prepatterning. Especially, the possibility to grow structures down to lower and lower resistivities may lead one to obtain smaller structures from p-Si than from n-Si. This opens the way to a variety of applications, from the manufacturing of micromechanical devices to the engineering of photonic-crystal materials.