Potential‐Enhanced Doping of Si Grown by Molecular Beam Epitaxy

Potential‐enhanced doping (PED) is a method by which the incorporation efficiencies of certain low sticking coefficient, coevaporated dopants can be enhanced during Si‐MBE. PED is implemented by application of a potential to the substrate during deposition. The applied potential is used to control instantaneous dopant incorporation, thereby permitting accurate control over doping levels over a wide dynamic range, as well as offering a powerful method of profile control. PED is especially effective with Sb doping, with enhancements by up to 1000 times being realized, thus permitting doping levels up to the solubility limit to be readily achieved. PED is less efficacious in the case of As doping obtained from III–V compound sources. The electrical, optical, and crystallographic quality of PED:Sb‐doped material is comparable to that of bulk Si. Doping transitions of < 50 A/decade have been obtained for transitions over several decades.