Surface functionalization strategies for monolayer doping

Due to limitations of ion-beam implantation for thin-body and 3D device geometries, techniques that allow for strict control over dopant diffusion are required. Advanced and conformal doping technologies are key for the continued scaling of semiconductor device past sub-10-nm dimensions. Monolayer doping (MLD) has been shown to satisfy the requirements for conformal and controllable doping on many materials ranging from devices fabricated from silicon and germanium to emerging replacement materials such as III-V compounds. Despite the enormous progress in the last decade, challenges still remain, especially with regard to suitable single-atom characterization techniques, surface roughness characterization, and investigation of the role of carbon. This article concisely summarizes the monolayer-doping technique and its application to dope silicon-, germanium-, and III-V-based materials and nanostructures to obtain shallow diffusion depths coupled with high-carrier concentrations.