Activation of aluminum implanted at high doses in 4H-SiC

We report an investigation of the electrical activation of aluminum implant ed at high dose in 4H-SiC. We show that at reasonably high temperature impl antation and annealing conditions, one activates about 37.5% of the implant ed species. Of course, the final (concentration-dependent) activation ratio differs slightly from this average value but varies only between 0.5 and 0 .25 when the targeted concentration increases from 3.33x10(18) to 10(21) cm (-3). Provided a standard mobility can be maintained, this results in fairl y low sheet resistance. The best (lowest) value obtained in this work is 15 m Omega cm at 700 K (95 m Omega cm at room temperature) for a 190-nm-thick layer implanted with 10(21) atoms cm(-3). In MESA-etched p-n junctions wit h a 100 mu m diameter, this resulted in a typical on-resistance of 1.5 m Om ega cm(2), mainly limited by the substrate and n(-) epitaxial layer. (C) 20 00 American Institute of Physics. [S0021- 8979(00)05216-6].