Defects and electrical properties in Al-implanted 4H-SiC after activation annealing*

Abstract

The defects and electrical properties in Al-implanted 4H-SiC after activation annealing (1600 °C–1800 °C) are investigated. High temperature annealing can reduce the ion implantation-induced damage effectively, but it may induce extended defects as well, which are investigated by using Rutherford backscattering spectroscopy (RBS/C), secondary ion mass spectroscopy (SIMS), and transmission electron microscopy (TEM) analyses. According to the ratio of the channeled intensity to the random intensity in the region just below the surface scattering peak (X min) and RBS/C analysis results, the ion implantation-induced surface damages can be effectively reduced by annealing at temperatures higher than 1700 °C, while the defects near the bottom of the ion-implanted layer cannot be completely annealed out by high temperature and long time annealing process, which is also demonstrated by SIMS and TEM analyses. Referring to the defect model and TEM analyses, an optimized annealing condition can be achieved through balancing the generation and elimination of carbon vacancies in the ion implanted layers. Furthermore, the electrical and surface properties are also analyzed, and the hole concentration, mobility, and resistivity are obtained through the Hall effect. The optimized activation annealing conditions of 1800 °C/5 min are achieved, under which the lower defects and acceptable electrical properties are obtained.