Investigation of the distribution of deep levels in 4H-SiC epitaxial wafer by DLTS with the method of decussate sampling

Abstract

• Z 1/2 defect typically exist in n-type 4H-SiC epitaxial layer. • Defect concentration uniformity of the epilayer is 5.74%. • Z 1/2 defect is uniformly distributed in 4-inch n-type 4H-SiC epitaxial layer. • Ti center did not appear at the temperature range from 80 K to 500 K. In this paper, Schottky structures were fabricated on the epitaxial wafers and the deep levels of the wafers were measured by deep level transient spectroscopy (DLTS). The thickness of the commercial n-type 4°off-axis 4H-SiC (0 0 0 1) epitaxial wafers was 100 μm, with a doping concentration of 2 × 10 14 cm −3 . Nine sample points were selected along with the direction of [1–100] and [11–20] on the wafer. Through the peak fitting analysis of the test results, the detailed information of deep level defects in the epitaxial layer was obtained. The typical deep level defect Z 1/2 was found, but Ti center did not appear, which indicates that Ti center was not introduced in our technological process. Defect concentration uniformity of the 4-inch 4H-SiC epitaxial wafer is 5.74%. The results demonstrate that although the concentration of Z 1/2 defect differs in different locations, but the difference is so small that Z 1/2 defect concentration can be considered to be evenly distributed across the wafer.