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 x 10(19) to 8 x 10(20)/cm(3) (0.39 mu m implanted thickness) and a conventional thermal annealing of 1950 degrees C/5 min. Implanted 4H-SiC layers of p-type conductivity and sheet resistance in the range of 1.6 x 10(4) to 8.9 x 10(2) Omega(square), corresponding to a resistivity in the range of 4.7 x 10(-1) to 2.7 x 10(-2) Omega 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 x 10(19)/cm(3) to 4 x 10(20)/cm(3). 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.