Capacitance spectroscopy study of deep levels in Cl-implanted 4H-SiC

We report on a deep level transient spectroscopy study of Cl-implanted n- and p-type 4H-SiC epilayers. Samples were electrically characterized after each step of an isochronal annealing series, between room temperature and 1800 degrees C, and twelve deep traps were detected. Of these, seven traps were found in n-type material, ranging from 0.15 to 1.6 eV below the conduction band minimum (E-C), and five were detected in p-type material, located between 0.5 and 1.7 eV above the valence band maximum (E-V). Besides the presence of the well known Z(1/2) and EH6/7 levels in n-type 4H-SiC and of the D-center in p-type samples, we found that Cl implantation gives rise to three new traps in n-type material at E-C - 0.37 eV, E-C - 1.06 eV, and E-C - 1.3 eV and one new level in p-type at E-V 0.97 eV. These traps are persistent after annealing at 1800 degrees C, and no data were found in the previous experimental studies reported in the literature. The possible involvement of Cl in the microscopic structure of these defects is discussed based on a depth profiling analysis of their concentration. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754854]