Abstract
After annealing in a H2 atmosphere at different temperatures, ⟨100⟩-oriented n-GaAs substrates were metallized with Au and Ti layers of different thicknesses to form Au/n-GaAs and Ti/n-GaAs Schottky diodes. The Schottky barrier height (SBH) variation and its dependence on subsequent N2 annealing for these Schottky diodes have been studied by different measurement techniques (I–V, C–V and BEEM) to obtain reliable values. These methods show that pre-metallization annealing leads to a less homogeneous metal semiconductor (MS) interface. In case of thick Au layers the effective barrier height is reduced as soon as the H2 annealing temperature reaches 300 °C. However, GaAs samples covered with thin Au layers or Ti layers do not exhibit such a barrier height reduction. The lower value in the case of thick Au layers is attributed to H+ groups, present at the interface due to the annealing in H2 atmosphere, forming interfacial dipoles with Au, leading to an inhomogeneous barrier and a decrease of the effective barrier height. It seems that these dipoles disappear again in the case of thin Au layers or are not formed with Ti. Post-metallization N2 annealing at higher temperatures lowers the barrier height for all samples. The resulting barrier inhomogeneities are explained and analysed using the bond polarization theory of Tung (2001 Phys. Rev. B 64 205310, 2001 Mater. Sci. Eng. R 35), a recent Schottky barrier formation model and the pinch-off model (Tung 1992 Phys. Rev. B 45 13509).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.