Low temperature epitaxial silicon films deposited by ion-assisted deposition

Ion-assisted deposition (IAD) is an advanced molecular beam epitaxy method that provides additional growth energy due to the use of a small fraction of accelerated Si-ions in the Si beam. At low deposition temperatures Tdep≤650 °C, the energetic contribution of ions with an energy of 20 eV improves the electronic quality of (100)-oriented epitaxial Si films as shown by an increase of the minority carrier diffusion length L. However, L of (111)-, (110)-, and (113)-oriented films decreases when using hyperthermal Si-ions. The density of extended defects in IAD films is found to be below 1×103 cm−2 on (100)-oriented films, independent of substrate temperature and deposition rate. At Tdep=460 °C, L displays a maximum at a high deposition rate of rdep=0.3 μm min−1, which correlates with a minimum in the density of point defects at the same rate.