Implantation and diffusion of phosphorous in germanium

In this work, we investigate the implantation and diffusion of phosphorous (P) in germanium (Ge). Ge wafers were implanted at two different doses (5 x 10(13) and 10(15) cm(-2)) and a range of energies (30, 50 and 150 keV). Part of the wafers was covered with a 40 nm silicon dioxide (SiO2) and an 80 nm silicon nitride (Si3N4) capping layer while the rest remained uncovered. Subsequently, the samples were furnace-annealed in an inert ambient (N-2) at 500 degrees C and a range of annealing times (30 min to 5 h). The experimental concentration profiles were obtained by secondary ion mass spectroscopy (SIMS). In the case of uncovered samples, substrate evaporation and significant phosphorous dose loss was observed, depending on the implantation and annealing conditions. At the lower implant dose, there is insignificant diffusion of phosphorous atoms in Ge, whereas at the higher implant dose, phosphorous exhibits a box profile consistent with previous experimental studies. (C) 2006 Elsevier Ltd. All rights reserved.