Deterministic single-ion implantation method for quantum processing in silicon and diamond

The actual potential of materials such as silicon and diamond, which are the key materials for quantum processing as well as the basic materials in transistors, has often been realized by adding dopants to modify their electrical or optical properties. This has usually been achieved through a doping process called the ion implantation method. In the future, silicon-based scaled-down transistors will contain a few dopants in the channel. It has been well known that the random distribution of dopants causes significant variations in transistor performance. Further, complementary metal-oxide-semiconductor (CMOS) technologies will require the placement of dopants in a predetermined location, which is referred to as atomistic dopant control. This chapter 4introduces deterministic doping, i.e., a single-ion implantation method, which enables sequential implantation of dopant ions into a fine semiconductor region until the desired number of ions is reached. Self-assembled monolayer doping with loaded dopants is also discussed. This method can help achieve sub-5-nm ultrashallow junctions with spike anneals. These techniques realize atomically controlled dopant profiles in silicon, diamond, and other materials, which could provide opportunities for single-dopant transport or single-photon source beneficial to quantum processing.