Structural stability of thermoelectric diffusion barriers: Experimental results and first principles calculations

This study demonstrates the feasibility of producing a tantalum nitride (TaN) thin film as a diffusion barrier and buffer layer for p-type bismuth telluride [(Bi,Sb)₂Te₃] thermoelectric devices. A network of TaN with nitrogen (N) incorporation is structurally more stable on (Bi,Sb)₂Te₃ than the conventional Ni diffusion barrier because of less inter-diffusion and a greater likelihood of stoichiometry in the TaN/(Bi,Sb)₂Te₃ interface. The atomic inter-diffusion between the barrier layers and (Bi,Sb)₂Te₃ was evaluated in terms of interface adhesion energy using nanoscratching, and proved with first-principles calculations.