First principles study of stability and thermoelectric response of GeH monolayer

Abstract

Thermoelectric characteristics of two-dimensional GeH structure have been studied using first-principles density functional technique and Boltzmann transport theory. Positive phonon modes and negative formation energy both attest to the stability of structure. A high value of elastic constant suggests strong chemical bonding and hence high mechanical strength. A direct band gap semiconducting character of GeH monolayer with 1.64 eV band gap is revealed by examination of electronic band structure. Flat conduction band in one direction and degenerate valence band near Fermi level improves density of states. As a consequence, both Seebeck coefficient and electrical conductivity shows excellent response and results in high power factor. At room temperature, the ZeT value of 5.51 (5.45) is obtained for p-(n) type doping, which shows its high practical capability of thermoelectric conversion. These findings suggest that GeH monolayer is an exciting possibility for 2D thermoelectric applications.