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 8C, 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 EH 6=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 À 0:37 eV; E C À 1:06 eV, and E C À 1:3 eV and one new level in p-type at E V þ 0:97 eV. These traps are persistent after annealing at 1800 8C, 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. V C 2012 American Institute of Physics. [http://dx.

Effect of Z1/2, EH5, and Ci1 deep defects on the performance of n-type 4H-SiC epitaxial layers Schottky detectors: Alpha spectroscopy and deep level transient spectroscopy studies

“…23,[34][35][36] The activation energy corresponding to peak #4 was found to be located at 1.04 eV below the conduction band edge. A defect level reported by Alfieri et al, 37 located at E c À 1.03 eV and designated as EH 5 , is the closest match with the Peak #4 observed in our case. Beyer et al has also detected similar defect level (E c À 1.07 eV) in 2.5 MeV electron irradiated 4H-SiC.…”

“…31 The activation energy of Peak #5 was found to be 1.30 eV. Alfieri et al 37 reported a similar defect center Ci1 in a chlorine implanted n-type 4H-SiC epitaxial layer. The Peak #6 was found to have the highest activation energy (2.40 eV) among all the defect centers observed in the DLTS scans and remains unidentified as the corresponding activation energy does not match with any known defect level in 4H-SiC that has been reported in the literature.…”

Local non invasive study of SiC diodes with abnormal electrical behavior

“…Considering the manufacturing scheme, we can conclude that these traps were induced by a high energy implantation of p-wells at the edge termination (as previously indicated). Similar effects have been observed in 4H-SiC [27][28][29] as well as in 6H-SiC [30,31] wafers, with all contributing to a higher capacitance of the SiC epilayer. In [27], such traps were attributed to intrinsic defects in the 4H-SiC epitaxial layers, while in [28,29] it was attributed to defects created during Cl implantation and proton irradiation, respectively.…”

Isochronal annealing on n-type 4H-SiC epitaxial schottky barriers and investigation of defect levels by deep level transient spectroscopy

“…A defect level reported by Alfieri et al [50] located at E c -1.03 eV and designated as EH 5 , is the closest match with the peak #3 observed in our case. Beyer et al has also detected similar defect level (E c -1.07 eV) in 2.5 MeV electron irradiated 4H-SiC [51].…”