Aluminum bonding between Si – Ge Thermoelectric Element and Molybdenum Electrode

Abstract

A new method that is low cost and produces highly reliable refractory bonds was developed for bonding Si – Ge thermoelectric devices and Mo electrodes. Aluminum foil was chosen as an alternative material to conventional Ag alloy paste, because of its cost advantages and bonding ability. Good wettability of Al to both the Si – Ge devices and Mo electrodes was achieved at a bonding temperature of 953 K. For 12.5 µm – thick Al foil, almost no degradation of the joint strength occurred after heat treatment at 823 K for 18000 s, because the reaction of the thin Al bonding layer to Si – Ge was completed during the bonding process. Comparable conversion efficiency of Si – Ge device was achieved between Al and Ag paste bonding.