Hydrogenation of GaAs on Si: Effects on diode reverse leakage current

Abstract

Plasma hydrogenation for 3 h at 250 °C of GaAs layers grown directly on Si substrates by metalorganic chemical vapor deposition, followed by a 5-min, 400 °C anneal to restore the passivated shallow donor electrical activity, increases the reverse breakdown voltage of Schottky diode structures from 2.5 to 6.5 V. This improvement appears to be a result of the passivation by atomic hydrogen of defects such as threading dislocations caused by the large (4%) lattice mismatch between GaAs and Si. A reduced Schottky barrier height is exhibited by hydrogenated samples, consistent with As depletion of the surface occurring during the long duration plasma processing.