Characterization of phosphorus doped n-type 6H-silicon carbide epitaxial layers produced by nuclear transmutation doping

Aluminum doped 6H-SiC epitaxial layers (p-type net doping: NA−ND=5.2×1015 cm−3, thickness 3 μm) on a p+ doped 6H-SiC substrate (NA−ND=1018 cm−3) were irradiated with neutrons in a nuclear reactor. The neutron fluences applied were 9.4×1019, 3.5×1020, and 6.4×1020 cm−2. The phosphorus impurity in SiC is produced by a nuclear (n,γ) reaction with the decay of Si31 to P31. The irradiated samples were subsequently annealed at temperatures between 800 and 1850 °C. The annealing behavior was studied by low temperature photoluminescence, Fourier transform infrared spectroscopy, and Hall effect and I–V and C–V measurements. After the annealing process the 6H-SiC p-type epilayer changed to n type resulting in a pn junction within the material. The properties of the pn junction were characterized.