Oxidation of thermoelectric Bi2Te3-based alloys by atomic layer deposition of Ru metal

Abstract

Despite the success of heterogeneous coatings of thermoelectric materials by atomic layer deposition (ALD), ALDgrown materials have been limited to oxides with high resistance. In this study, we attempted the nanoinclusion of metals in thermoelectric materials by the deposition of Ru metal on Bi0.4Sb1.6Te3 powders using an ALD with a Ru precursor and O-2. As the number of Ru ALD cycles increased, the quantity of deposited Ru increased, and the grain size of Bi0.4Sb1.6Te3 in the sintered Bi0.4Sb1.6Te3 decreased. However, ALD resulted in the oxidation of the Bi0.4Sb1.6Te3 powders because of the high-temperature growth at 300 degrees C with O-2 injection. The thermoelectric properties of the Ru-coated Bi0.4Sb1.6Te3 pellets were governed by oxidation rather than Ru inclusion. This study demonstrates that an oxidation-free ALD process is necessary for the nanoinclusion of Ru in Bi2Te3-based alloys using ALD.