Experimental results showed that the deep-level centers in semi-insulating GaAs decreased with improved stoichiometry. The electrical resistivity doubled when the concentration of EL2 centers was decreased by 50%. Micro-gravity growth experiments also showed that improved stoichiometry resulted in a decrease in deep-level centers.

Relationship between deep-level centers and stoichiometry in semi-insulating gallium arsenide L.Lin, N.Chen, X.Zhong, H.He, C.Li: Journal of Applied Physics, 1998, 84[10], 5826-7