Fig. 5: Conductive and wear performance of the NbMoTaW coatings on AFM probe tips.

a Uncoated (bare silicon tip), Nb₂₅Mo₂₅Ta₂₅W₂₅, Nb₁₅Mo₃₅Ta₁₅W₃₅ changes in surface morphology before and after wear. b In-use wear resistance under simultaneous mechanical loading and electrical bias. c Required bias to achieve the same current level for different thickness. Nb₁₅Mo₃₅Ta₁₅W₃₅ shows lower bias than Nb₂₅Mo₂₅Ta₂₅W₂₅, indicating the former has the better surface conductivity. The error bars represent the standard deviation. d In-use wear performance of a commercial conductive (Pt/Ir coated) AFM probe with that of a Nb₁₅Mo₃₅Ta₁₅W₃₅ coated probe. e Comparison of the hardness and conductivity of Nb₂₅Mo₂₅Ta₂₅W₂₅, Nb₁₅Mo₁₅Ta₃₅W₃₅, and Nb₁₅Mo₃₅Ta₁₅W₃₅ films with those of other high entropy alloy films and hard coating films in the literature^{6,11,12,26,27,28,29,30,31,35,36,37,57,58,59,60,61}. Note that only thin film samples are considered.