Electrical and topographical characterization of aluminum implanted layers in 4H silicon carbide

Electrical parameters and surface topography of aluminum (Al) implanted layers in 4H silicon carbide (SiC) are analyzed. The implantation is conducted for temperatures from room temperature up to 1000 °C. The impact of the post implantation annealing step on the Al implanted layers is investigated for two different annealing systems, a furnace system and a lamp system. The implanted layers are characterized in detail by atomic force microscopy and resistivity measurements. A model based on resistivity data is developed for the determination of activation and compensation and is discussed in order to get a better insight into the influence of the annealing step on the electrical parameters (e.g., hole mobility). In particular, the effect of elevated implantation temperatures on resistivity is identified. Additionally, the surface topography is examined regarding the annealing gas atmosphere. For that, a silicon carbide coated graphite crucible is used to achieve a silicon overpressure during annealing. The effectiveness of this crucible is identified by modeling. Measurements confirm the modeling results, that such a crucible prevents surface degradation only in the lamp system with heating rates of several 1000 K/min, and not in the furnace with heating rates in the range of some 10 K/min. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)