Electrical effects of atomic hydrogen incorporation in GaAs-on-Si

We have introduced atomic hydrogen by two methods into GaAs layers epitaxially grown on Si substrates, namely, by exposure to a hydrogen plasma or by proton implantation. In both cases, when proper account is taken of shallow dopant passivation or compensation effects, there is a significant improvement in the reverse breakdown voltage of simple TiPtAu Schottky diodes. Proton implantation into undoped (n=3×1016 cm−3) GaAs-on-Si leads to an increase in this breakdown voltage from 20 to 30 V, whereas plasma hydrogenation improves the value from 2.5 to 6.5 V in n-type (2×1017 cm−3) GaAs-on-Si. Annealing above 550 °C removes the beneficial effects of the hydrogenation, coincident with extensive redistribution of the hydrogen. This leaves an annealing temperature window of about 50 °C in the H-implanted material, in comparison to 150 °C for the plasma-hydrogenated material. The hydrogen migrates out of the GaAs to both the surface and heterointerface, where it shows no further motion even at 700 °C. Trapping in the GaAs close to the heterointerface is shown to occur at stacking faults and microtwins, in addition to extended dislocations.