Conventional thermal annealing for a more efficient p-type doping of Al⁺ implanted 4H-SiC

The p-type doping of high purity semi-insulating 4H polytype silicon carbide (HPSI 4H-SiC) by aluminum ion (Al+) implantation has been studied in the range of 1 × 1019to 8 × 1020/cm3(0.39 μm implanted thickness) and a conventional thermal annealing of 1950 °C/5 min. Implanted 4H-SiC layers of p-type conductivity and sheet resistance in the range of 1.6 × 104to 8.9 ×102Ω□, corresponding to a resistivity in the range of 4.7 × 10−1to 2.7 × 10−2Ω cm have been obtained. Hall carrier density and mobility data in the temperature range of 140–720 K feature the transition from a valence band to an intraband conduction for increasing implanted Al ion concentration from 1 × 1019/cm3to 4 × 1020/cm3. A 73% electrical activation, 31% compensation and 146 meV ionization level have been obtained using a best-fit solution of the neutrality equation to Hall carrier data for the lowest concentration.