An Overview of Doping Strategies in Si:MBE

Abstract

ABSTRACTThis paper reviews the diverse methods used to achieve doping during MBE of Si and SiGe, and the incorporation processes involved. The optimum choice of dopant and methodology depends on the most appropriate growth conditions for a given structure. At growth temperatures exceeding 750°C, Potential Enhanced n-type doping of coevaporated Sb is capable of achieving high resolution structures, at doping levels up to mid-1019 cm−3. At lower temperatures, such as those most suited to SiGe growth, Sb-doping becomes a formidable challenge, due to the high accumulated equilibrium coverages required. Low energy ion implantation appears to be the favoured route for good control, p-type B-doping can readily be achieved by coevaporation of compounds or, to avoid oxygen incorporation at low temperatures, the element. A “designer” chart for B-doping of Si is presented.