After exposure to hydrogen plasma and chemical etching to remove layers of different thicknesses, n-type GaAs wafers with 〈100〉 and 〈110〉 orientation were deposited with Au to form Au/(n-GaAs) Schottky barriers (SB’s). After zero-bias annealing (ZBA), the Schottky-barrier height (SBH) of the Au/(n-GaAs) SB’s containing hydrogen falls; after reverse-bias annealing (RBA), the SBH rises; and the SBH is reversible within experimental precision in at least three ZBA-RBA processes. Furthermore, the control effect of zero-bias annealing and reverse-bias annealing on the Schottky barrier height depends quantitatively on the orientation of the GaAs wafer and the thickness of the layer removed by chemical etching before deposition of Au. But the Schottky-barrier height of a control Schottky-barrier that is not subject to hydrogen exposure changes little during zero-bias annealing or reverse-bias annealing processes. It is also found that besides the SBH the effective Richardson coefficient of the SB containing hydrogen has a one-to-one correlation with the reverse bias of the RBA (100 °C, 2 h). Experiments strongly support the fact that the hydrogen contained in the SB is essential for the above ZBA-RBA effect. We have suggested a physical model to explain why hydrogen can reduce the Schottky-barrier heights and result in the ZBA-RBA effect of Au/(n-GaAs) Schottky barriers.

• Received 19 July 1993

DOI:https://doi.org/10.1103/PhysRevB.48.17986