Schottky barrier heights of metals contacting to p-ZnSe

Schottky barrier heights (SBH’s) of a variety of metals (In, Cd, Nb, Ti, W, Cu, Ag, Au, Ni, Pt, and Se) contacting to p-ZnSe grown by a molecular beam epitaxy method were measured by an internal photoemission, capacitance–voltage (C–V), and/or current density–voltage (J–V) method. The internal photoemission method could not measure accurately the SBH’s of these metals due to a strong interference of the monochromatic incident light in the p-ZnSe epilayer. The C–V method measured a SBH value of 1.23 eV for the Au contact and 1.13 eV for the Ni contact, but did not measure the SBH’s of other metals due to strong hysteresis of the C–V curves. The SBH’s of these metals were successfully measured by the J–V method to be 1.2±0.1 eV. The present experiment showed that the SBH values were independent of the work functions of the contact metals, indicating that the Fermi-level could be pinned at the p-ZnSe/metal interface. In addition, turn-on voltages conventionally used to evaluate the electrical properties of the contact metals were found to be very sensitive to the SBH values.