Doping techniques for fin-like field effect transistors (FinFETs) are disclosed herein. An exemplary method includes forming a fin structure, forming a doped amorphous layer over a portion of the fin structure, and performing a knock-on implantation process to drive a dopant from the doped amorphous layer into the portion of the fin structure, thereby forming a doped feature. The doped amorphous layer includes a non-crystalline form of a material. In some implementations, the knock-on implantation process crystallizes at least a portion of the doped amorphous layer, such that the portion of the doped amorphous layer becomes a part of the fin structure. In some implementations, the doped amorphous layer includes amorphous silicon, and the knock-on implantation process crystallizes a portion of the doped amorphous silicon layer.