Atomic Layer Deposition of Highly Conducting NiS ₂ Thin Films from Elemental Sulfur

ABSTRACT A novel atomic layer deposition (ALD) process for highly conducting nickel disulfide thin films is introduced. This simple, sustainable and safe deposition process is based on two solid precursors, nickel acetylacetonate (Ni(acac) 2 ) and elemental sulfur. The process yields single‐phase NiS 2 thin films in the deposition temperature range from 220°C to 270°C, with an appreciably high growth rate of ca. 3.42 Å per cycle. The as‐deposited films are highly crystalline and chemically homogeneous. Room‐temperature electrical conductivity values up to 2.8 × 10 3 S/m and optical bandgap values in the range of 0.8–0.9 eV are measured for the films. The distinctly high surface area of the films, caused by flake‐like nanostructures, together with the excellent electrical properties makes the present ALD‐grown NiS 2 thin films attractive for various electrochemical applications, such as catalysts for hydrogen evolution reaction.