Controlling Defect Chemistry in InTe by Saturation Annealing

Abstract

Achieving a precise control of defects in chalcogenide semiconductors is paramount to optimizing their thermoelectric properties. Recently, p-type InTe has emerged as a potential candidate for thermoelectric applications in power generation, mainly due to its extremely low lattice thermal conductivity. Here, we show that the concentration of inherent In vacancies in both single-crystalline and polycrystalline InTe samples can be successfully controlled through saturation annealing. This process, performed on both the In-rich and Te-rich sides of the solidus line at 943, 893, 843, and 943 K, respectively, results in variations in the hole concentration from 4.9 to 8.5 × 10 19 cm −3 at 300 K. This narrow density range suggests that the defect chemistry in InTe plays a less critical role in determining its thermoelectric properties compared to other state-of-the-art thermoelectric chalcogenides. The increased partially degenerate character of transport with increasing annealing temperature lowers the thermoelectric performance, with a peak ZT value of 0.9 achieved at 710 K in as-synthesized InTe.

Influence of Cu insertion on the thermoelectric properties of the quaternary cluster compounds Cu3M2Mo15Se19 (M = In, K) and Cu4In2Mo15Se19

“…These low mobility values can be primarily attributed to the strongly disordered character of the Cu + cations residing in the intercluster voids, as observed in other tunnel-like compounds such as InTe or Tl 0.6 Mo 3 S 5 for instance. 69–73…”

“…These low mobility values can be primarily attributed to the strongly disordered character of the Cu + cations residing in the intercluster voids, as observed in other tunnel-like compounds such as InTe or Tl 0.6 Mo 3 S 5 for instance. [69][70][71][72][73] The total thermal conductivity k of the three compounds as a function of temperature is shown in Fig. 9(a).…”

Crystal Structure, Electronic Transport, and Improved Thermoelectric Properties of Doped InTe

“…The thermal conductivity of InTe is much lower than many well-known cubic rock salt chalcogenides such as PbTe and SnTe. ,, The ultralow thermal conductivity of InTe has been attributed to the strong anharmonicity induced by the weakly bound In 1+ ions with dynamical lone pair activity. , Inelastic scattering experiments combined with systematic theoretical calculations have been conducted to reveal anharmonic low-lying phonon modes responsible for ultralow thermal conductivity and their detailed microscopic origin. , Despite the ultralow thermal conductivity, InTe is much less investigated as a TE material than (Pb, Sn)Te due to its poorer TE performance. TE properties of both polycrystalline and single crystalline InTe samples have been reported, ,− but the zT values are usually lower than unity owing to relatively poor electrical properties. Some experimental efforts have been made to improve zT through introducing a minor Sb phase and p-type doping with Pb, Ga, Cd, Cu, Na, and CuInTe 2 .…”