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 de fects with their electrical characteristics in semiconductors. Interes ting results that directly and clearly show the influence of micropipe s on the minority carrier diffusion length were obtained in both p- an d n-type 6H-SiC. The method is based on electron-beam induced current (EBIC) measurements in planar structures. Values of hole diffusion len gth in defect free regions of n-type 6H-SiC, with a doping concentrati on of 1.7 x 10(17) cm(-3), ranged from 1.46 to 0.68 mu m. These values were reduced to below 0.1 mu m at the center of large defects. In add ition, measurements on p- type 6H-SiC resulted in electron diffusion l engths ranging from 1.42 to 0.8 mu m which also showed drastic reducti ons near defects. Our planar mapping technique measures diffusion leng ths along a linescan. This linear map is then overlaid onto the EBIC i mage, allowing direct visualization of defects and their effect on min ority carrier diffusion lengths. (C) 1998 American Institute of Physic s. [S0021-8979(98)01919-7].