Semiconducting High-Entropy Chalcogenide Alloys with Ambi-ionic Entropy Stabilization and Ambipolar Doping
Zihao Deng, Alan Olvera, Joseph Casamento, Juan Lopez, Logan Williams, Ruiming Lu, Guangsha Shi, Pierre F. P. Poudeu, Emmanouil Kioupakis
Abstract
Entropy stabilization is a novel materials-design paradigm to realize new compounds with widely tunable properties. However, almost all entropy-stabilized materials so far are either conducting metals or insulating ceramics, with a clear dearth in the semiconducting regime. Here, a new class of the multicationic and -anionic entropy-stabilized chalcogenide alloys based on the (Ge,Sn,Pb)(S,Se,Te) formula are synthesized and characterized experimentally. The configurational entropy from the disorder of both the anion and the cation sublattices reaches a record value of ∼2.2 R mol–1 for the equimolar composition and stabilizes the single-phase solid solution. Theoretical calculations and experiments both show that the synthesized alloys are thermodynamically stable at the growth temperature and kinetically metastable at room temperature, segregating by spinodal decomposition at moderate temperatures. Doping and electronic transport measurements verify that the synthesized materials are ambipolarly dopable semiconductors, which pave the way for the wider adoption of entropy-stabilized chalcogenide alloys in functional applications.