Thermoelectric performance enhancement in cadmium-combined GaN nanosheets

Abstract

By employing density functional theory (DFT) and the NEGF method, this paper provides a detailed first-principles study on the thermoelectric properties of cadmium (Cd)-doped gallium nitride (GaN) nanosheets. The goals include understanding the impact of Cd doping on the GaN nanosheets’ electrical parameters, thermoelectric efficiency, and charge transport features. Cd doping has a significant effect on Ga–N covalent bonds due to considerable electronic delocalization, altering bonding characteristics, and enhancing carrier mobility, as shown by charge density and electron localization function (ELF) analyses. Cd incorporation improves charge transfer, decreases the bandgap, and thus enhances conductivity, as indicated by the transmission spectra. Moreover, the thermoelectric figure of merit (ZT), power factor (S²σ), and the Seebeck coefficient all show significant enhancement of thermoelectric performance, especially within the GaN-3Cd configuration. ZT values reaching 0.048 and a power factor more than 3.5 × 10⁴ pW K⁻² were observed. While the thermal conductivity increases modestly with the Cd concentration, it remains low enough to sustain thermoelectric efficiency. These findings illustrate that Cd-doped GaN nanosheets could be promising candidates for thermoelectric and nanoelectronic devices.