Defect Dynamics in III-V Semiconductor

Native defects play an important role in compound semiconductors. Their relative abundance is controlled by nonstoichiometry and thermodynamic considerations. We have investigated a large number of point defects and defect pairs in GaAs. 

By evaluating their electronic structure and their total configurational energies we can study defect reactions and from these predict abundances as a function of nonstoichiometry and background doping. Since most defects introduce one or more deep levels, carriers can be trapped or released and thereby strongly influence the equilibrium of defect reactions. 

In fact, rather unusual dynamic systems emerge for simple pair reactions exhibiting for instance bistable and metastable configurations. One such system, the Ga vacancy and As vacancy - As/Ga antisite pair is studied in detail. Preliminary results are also given for the antisite-interstitial pair. Both complexes show some features with similarities to the EL2 center.