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

Abstract

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 ∘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 (EC), and five were detected in p-type material, located between 0.5 and 1.7 eV above the valence band maximum (EV). Besides the presence of the well known Z1/2 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 EC−0.37 eV, EC−1.06 eV, and EC−1.3 eV and one new level in p-type at EV+0.97 eV. These traps are persistent after annealing at 1800 ∘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.