Electrical activation of nitrogen heavily implanted 3C-SiC(100)

A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the band-gap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ∼6x1020cm-3 at 20K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5x1019cm-3, donor level 15meV) to ∼12% for 6x1020cm-3. Free donors are found to saturate in 3C-SiC at ∼7x1019cm-3. The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (∼1.4mΩ.cm) has been observed for medium doped (4x1019cm-3) sample with PIA 1375 °C 2 h without a SiO2 cap