ION IMPLANTATION EFFECTS OF NITROGEN, BORON, AND ALUMINUM IN HEXAGONAL SILICON-CARBIDE

The effects of the implantation of **1**4N** plus , **1**1B** plus , and **2**7Al** plus ions in hexagonal 6H SiC crystals were studied through optical and microanalytical methods. The optical data taken for 60 keV **1**4N** plus implants indicate that little damage occurs up to a fluence of 10**1**4 cm** minus **2. For fluences between 10**1**4 cm** minus **2 and 1. 3 multiplied by 10**1**5 cm** minus **2, there is a rapid increase of the optical absorption below similar 3 eV with a broad absorption tail extending into the near infrared. For larger fluences, the optical absorption close to the band edge actually decreases. The band edge shifts to lower energies with increasing fluence. The radiation damage begins to anneal at low temperatures but is not completely removed until annealing at 1400 C. The impurity profiles measured before and after annealing for crystals irradiated with different fluences show that the distribution of the impurities is broader than predicted by the LSS theory and changes with fluence. Upon annealing the impurities migrate toward the surface.