LOW-TEMPERATURE SI MOLECULAR-BEAM EPITAXY - SOLUTION TO THE DOPING PROBLEM

A major problem in group IV molecular beam epitaxy (MBE) is the difficulty to incorporate and control dopants due to the low incorporation probability and strong segregation in Si at typical growth temperatures. It is demonstrated here that growth at low temperatures yields a solution to this doping problem making thermal, coevaporative doping with excellent control possible in Si MBE without the need for any post-growth annealing. Unity incorporation and activation of Sb with concentrations reaching 5×1019 cm-3 are achieved for epitaxial growth of Si on Si(100) at temperatures of 325°C. Hall electron mobilities in the films are close to bulk values indicating the high quality of the films. Capacitance-voltage measurements on Sb δ-doped films have full widths at half maximum of ≲50 Å, the narrowest Sb-doping profiles in Si determined with an electrical technique.