High effective Schottky barriers on n-type InP using Zn-based metallizations and rapid thermal annealing

Abstract

Surface barrier diodes using different Zn-based metallizations, which were alloyed using rapid thermal annealing in order to make low-leakage, high barrier metal-semiconductor diodes on n-type InP, have been studied. The electrical properties of diodes using Cr in between the Zn layer and the InP are poor, because Cr and P forms a diffusion barrier-like layer adjacent to the semiconductor surface, which is hard to overcome and, more important, shunts the diode because it forms low effective barriers to n-type InP. For Au/Cr/Zn/Au/lnP diodes, high effective Schottky barriers of 0.76 eV from J-V characteristics and 1.23 eV from C-V characteristics have been measured for the same barrier diodes, indicating that the surface is not fully covered with the high effective barrier height interfacial phase, but that lower effective barrier height interfacial phases are also present. The dominant transport mechanism of carriers across these metal-semiconductor diodes is found to be thermionic emission from J-V-T measurements. and the leakage current density measured at -1 V is 8*10-6-10-5 A cm-2. From depth profiling using Rutherford backscattering spectrometry and near-surface imaging using scanning electron microscopy it is seen that In is depleted from the InP surface due to Zn-P/Cr-P stable phase formation and that it either agglomerates at the surface of the metallization or is incorporated into the Au layer forming stable Au-In and In-O compounds.