Non-destructive Three-dimensional Imaging of Extended Defects in 4H-SiC

Three-dimensional (3D) imaging of extended defects in 4H-SiC epilayers was achieved by optical second-harmonic generation (SHG) and two-photon-excited photoluminescence (2PPL). The SHG method provided 3D images of 3C-inclusions with a spatial resolution of about 1.3 mu m. Using the 2PPL method, we conducted the 3D imaging of 3C-inclusions, 8H stacking faults, and single Shockley stacking faults in the epilayers. The band-edge emission of 2PPL enabled the 3D imaging of threading screw dislocations (TSDs), threading edge dislocations (TEDs), and basal-plane dislocations (BPDs). Since band-edge emission quenches near defects, these dislocations can be visualized as dark contrasts on a bright background. The perspective view of TSDs and TEDs extending similar to 200 mu m from the surface was given by inverting the intensity of a 3D image block of band-edge emission. The tilt angles of TSDs and TEDs in 4H-SiC epilayers were also measured and the mechanisms governing the line directions of TEDs and TSDs were discussed.