J-V characteristics of Al+ ion implanted p(+)/n 4H-SiC diodes annealed in silane ambient at 1600 degrees C

Al+ implanted p(+)/n 4H-SiC diodes were realized via planar technology. The p(+)/n junctions were obtained by hot implantation at 400° C, followed by a post implantation annealing at 1600° C in Silane ambient. 136 diodes and other test structures were measured: the current voltage curves and the resistivity of the implanted layer were investigated at room temperature. The majority of the measured diodes had a turn on voltage of about 1.75 V, a forward characteristic with exponential trend and ideality factor equal to 1.2, and a very. low spread in the distribution of the reverse leakage current values at -100V. The average reverse leakage current value is (9.7 ± 0.4) x 10(-9) A/cm(2). The breakdown voltage of these diodes approached the theoretical value for the use epitaxial 4H-SiC layer, i.e. 0.75 - 1.0 kV. All these positive results are penalized by the high resistivity value of the implanted Al+ layer, which amounts to 11 Ω• cm that is one order of magnitude higher than the desired value.