Fig. 4: Electrical transport analysis for the as-prepared Ge_0.94Bi_0.05Te + x wt% TiB₂ samples.

a Carrier concentration and mobility. b Comparison of carrier mobility in this work with different GeTe-based thermoelectrics^{11,16,17,24,28,30,32,33,38} (The theoretical limit is calculated using the single parabolic band model at 300 K). c Schematic of the interfacial band structure before and after contact. d Seebeck coefficient plot against carrier concentration based on the SPB model at 300 K. e Longitudinal elastic modulus derived from the sound velocity method and the mixture rule (The pink region represents the contribution from the load transfer effect, and the inset describes the interfacial constraint effect). f Calculated mean free path of carriers and relative deformation potential.