Aging effects in GaAs Schottky barrier diodes

The stability of the barrier height of Au/W/GaAs and Au/Pt/Ti/GaAs Schottky barriers under long-term biasing conditions is discussed. Both barrier types exhibit decreases in barrier height under long-term reverse bias conditions, with the changes seen for the Au/W/GaAs diodes (30-50 MeV) much greater than those for the Au/Pt/Ti/GaAs diodes (5 MeV). The changes in barrier height have a characteristic logarithmic dependence on time. Recovery of the barrier height occurs over a period of days in a zero bias condition, or in an accelerated manner under forward biasing for both sets of samples. A preliminary Auger study has correlated the presence of oxide at the interface with the barrier height shift observed, and this oxide is presumably involved in the formation/destruction of interface states which are responsible for the change in barrier height