Realization of non-equilibrium process for high thermoelectric performance Sb-doped GeTe

Discordant nature of Cd in GeTe enhances phonon scattering and improves band convergence for high thermoelectric performance

“…The power factor improvement is due to the large effective mass, which is enabled by the band convergence in Cd-doped Cd x -Ge 1Àx Te. To demonstrate this convincingly, the effective mass (m*) was estimated based on a single parabolic band approximation (SPB) 40,47 and the results are shown in Table 1. Specically, the effective mass increases from 1.44m 0 for pristine GeTe to 2.32m 0 for the sample with x ¼ 0.05.…”

Positive Effect of Ge Vacancies on Facilitating Band Convergence and Suppressing Bipolar Transport in GeTe‐Based Alloys for High Thermoelectric Performance

“…The Bi and Sb have been widely used to reduce the hole concentration of GeTe due to their donor dopant nature. [ 29–33 ] Other doping or alloying with Pb, [ 25,34–36 ] Se, [ 30,37–39 ] Bi‐Sb, [ 40 ] Bi‐Cu, [ 41 ] Mn‐Bi, [ 42 ] Mn‐Sb, [ 43 ] Pb‐Sb, [ 28,44 ] Pb‐Bi, [ 45 ] Cd‐Bi, [ 46,47 ] Sb‐Zn, [ 48 ] Sb‐In, [ 49 ] Bi 2 Te 3 , [ 23,26 ] Sb 2 Te 3 , [ 50 ] and AgSbTe 2 [ 51,52 ] have also been widely applied to optimize the carrier density and to reduce κ lat for enhancing the ZT of GeTe‐based alloys. Combined with the synergic effects of carrier‐density optimization, band engineering and phonon engineering strategies, many GeTe‐based alloys with peak ZT of around 2 have been reported recently.…”

Realizing a stable high thermoelectric zT ∼ 2 over a broad temperature range in Ge1−x−yGaxSbyTe via band engineering and hybrid flash-SPS processing

“…xSbxTe, 41,42 Ge1-xAgxTe, 43 Ge1-xMnxTe, 44,45 Ge1-x-ySnxPbyTe, 46 Ge1-xSbxTe1−ySey, 47 GeTe-GeSe-GeS, 48 Ge1-x-yBixSbyTe, 49 Ge1-x-yBixInyTe 25 and more recently Ge0.9-yPb0.1BiyTe. 50 The crystal structure of GeTe-based compounds undergoes a second-order ferroelectric structural transition from rhombohedral symmetry (low temperature phase) to cubic symmetry (high temperature phase) at around 700 K. 51 Motivated by the results of Wu et al on Ge1-xInxTe, 39 showing that the introduction of resonant levels in the vicinity of the Fermi level due to indium doping leads to a reasonably high zT in GeTe (zT  1.3 at 630 K), we here have tried to explore the effect of another group 13 element, namely Ga on the TE performance of GeTe.…”