High resistivity interfacial layers due to compensation by Sulfur in (Al,Ga)As devices

In p-n junctions grown by LPE in the (Al,Ga)As system, high concentrations of Sulfur can accumulate on the p side of the junction. As a result, a closely compensated, high resistivity region can extend for 0.1-1.0 µm into the p layer. Since sulfur creates deep electron traps in Al0.4Ga0.6As with a thermal activation energy in bulk p-type material of 0.2 eV, both electrical and optical properties of (Al,Ga)As diode devices can be affected by the interfacial sulfur concentrations.