Sputter-induced defects in Zn-doped GaAs Schottky diodes
Schottky barrier diodes are made by ac magnetron deposition of Au on p-type GaAs substrates. Sputtering causes donor-like defects in the surface region of semiconductors, and these donor-like states compensate mostly the Zn shallow acceptor states over distances of 200 nm below the surface. These defects are attributed to the As Frenkel pairs VAs?Asi with an energy level at 0.27 eV below the conduction band. The As Frenkel pairs are responsible for the Fermi level pinning at metal?semiconductor interfaces and also for the observed change in barrier height in sputtered GaAs material.