Molecular doping (MD) is a doping method based on the use of liquid solutions. The dopant precursor is in liquid form and the material to be doped is immersed in the solution. During the immersion process, the molecule containing the dopant atom is deposited on the surface of the material forming a self-assembled monolayer, that is, ordered and compact. Through a subsequent heat treatment, the molecule decomposes and the dopant diffuses.
Since the precursor is in liquid form, MD intrinsically allows conformal doping, even in porous or hollow structures. Furthermore, the density and the positions of the dopant atoms on the Si surface are fixed by the self-assembly mechanism, allowing to eliminate all the problems related to the statistical arrival at the nanometric scale of the dopant atoms on the Si surface, as occurs in traditional ion implantation. A further advantage consists in the fact that the method uses low cost and low environmental impact materials and processes.
Italy, PCT