Laser Annealing of P and Al Implanted 4H-SiC Epitaxial Layers

This work describes the development of a new method for ion implantation induced crystal damage recovery using multiple XeCl (308 nm) laser pulses with a duration of 30 ns. Experimental activity was carried on single phosphorus (P) as well as double phosphorus and aluminum (Al) implanted 4H-SiC epitaxial layers. Samples were then characterized through micro-Raman spectroscopy, Photoluminescence (PL) and Transmission Electron Microscopy (TEM) and results were compared with those coming from P implanted thermally annealed samples at 1650-1700-1750 °C for 1 h as well as P and Al implanted samples annealed at 1650 °C for 30 min. The activity outcome shows that laser annealing allows to achieve full crystal recovery in the energy density range between 0.50 and 0.60 J/cm². Moreover, laser treated crystal shows an almost stress-free lattice with respect to thermally annealed samples that are characterized by high point and extended defects concentration. Laser annealing process, instead, allows to strongly reduce carbon vacancy (V_C) concentration in the implanted area and to avoid intra-bandgap carrier recombination centres. Implanted area was almost preserved, except for some surface oxidation processes due to oxygen leakage inside the testing chamber. However, the results of this experimental activity gives way to laser annealing process viability for damage recovery and dopant activation inside the implanted area.