Mapping of crystal defects and the minority carrier diffusion length in 6H–SiC using a novel electron beam induced current technique

We report on a mapping technique used to correlate the structure of defects with their electrical characteristics in semiconductors. Interesting results that directly and clearly show the influence of micropipes on the minority carrier diffusion length were obtained in both p- and n-type 6H–SiC. The method is based on electron-beam induced current (EBIC) measurements in planar structures. Values of hole diffusion length in defect free regions of n-type 6H–SiC, with a doping concentration of 1.7×10¹⁷ cm^-3, ranged from 1.46 to 0.68 μm. These values were reduced to below 0.1 μm at the center of large defects. In addition, measurements on p-type 6H–SiC resulted in electron diffusion lengths ranging from 1.42 to 0.8 μm which also showed drastic reductions near defects. Our planar mapping technique measures diffusion lengths along a linescan. This linear map is then overlaid onto the EBIC image, allowing direct visualization of defects and their effect on minority carrier diffusion lengths. © 1998 American Institute of Physics.