DETERMINATION OF DONOR AND ACCEPTOR LEVEL ENERGIES BY ADMITTANCE SPECTROSCOPY IN 6H SIC

Admittance and deep level transient spectroscopy (DLTS) measurements w ere taken on n- and p-type Schottky diodes in order to determine the a ctivation energies of both shallow (aluminium and nitrogen) and deep l evels in 6H SiC epitaxial layers. A dependence on the lattice sites is found for N and suggested for Al. For N the activation energies are 8 2 and 137 meV in the hexagonal and cubic sites respectively. For Al, t he values could be 0.22 and 0.25 eV respectively. DLTS analysis shows the presence of deep levels in low concentrations. Finally, we show th at assuming a two-level structure of the doping impurities, the carrie r concentration can be well predicted as a function of temperature so that it is possible, from current-voltage measurements of junction fie ld effect transistors, to determine the power law dependence of mobili ty on temperature in n-type material.