BALLISTIC-ELECTRON-EMISSION MICROSCOPY STUDY OF SCHOTTKY CONTACTS ON 6H-SIC AND 4H-SIC

We have performed ballistic-electron emission microscopy (BEEM) on (Pd ,Pt)/ (6H,4H)-SiC(0001) Schottky contacts. Schottky barrier heights (S BHs) determined from the BEEM data using the Bell-Kaiser model are 1.2 7 eV/1.34 eV (Pd/Pt) for 6H- and 1.54 eV/1.58 eV for 4H-SiC. Our measu rements also give the first direct evidence of a second conduction ban d minimum (CBM) on 4H-SiC about 0.14 eV above the overall CBM. Spatial inhomogeneity of SBHs were examined and shown to be no larger than th e fitting error due to the system noise. Additionally, enhanced ballis tic transmittance was observed over a region intentionally stressed by injecting high kinetic energy (10 eV above EF) hot electrons using BE EM in the Pt/4H-SiC sample. (C) 1998 American Institute of Physics.