INTERNAL-PHOTOEMISSION MICROSCOPY (IPEM) - MICROSCOPIC CHARACTERIZATION TECHNIQUE FOR BURIED THICK-METAL SEMICONDUCTOR INTERFACES/

We have developed internal-photoemission microscopy (IPEM) which is ca pable of revealing microscopic inhomogeneity in SBH's at thick-metal/s emiconductor interfaces, which had not been disclosed by the conventio nal current-voltage (I-V) or capacitance-voltage (C-V) techniques. Inh omogeneous degradation of Ti/Pt/Au contacts to GaAs was shown by using this technique. In this experiment, the IPEM results revealed that lo cal formation of an Au-Ga alloy is responsible for the degradation of macroscopic I-V characteristics of the diodes. SBH inhomogeneity at ep itaxial-Al/Si(111)interfaces was clearly observed after annealing at t emperatures 450-550 degrees C. I discussed the discrepancy between SBH values determined by the I-V and C-V methods in relation to microscop ic IPEM images of several stages of annealing. IPEM can apply to optim ization of multilayered semiconductor contacts. It has been shown that the combination between IPEM and the test sample with a tapered first Ni-layer as well as an Al-layer is an effective way of optimizing Al/ Ni/Al/n-InP Schottky contacts.