Nonequilibrium Layered PbS Stabilized by Sn Doping: Bipolar Semiconductors with Low Thermal Conductivity
Year: 2024
Type: article
Abstract: Layered Sn- and Ge-based monochalcogenides have been known as promising semiconductor materials with appropriately narrow band gaps close to those of Si and GaAs. On the other hand, Pb-based ones possess much narrower band gaps and adopt the cubic rock-salt (RS)-type structure under ambient conditions, and their layered structures are considered thermodynamically unstable. We recently succeeded in the stabilization of GeS-type layered structures in lightly Sn-doped PbS by the combination of a high-temperature solid-state reaction with thermal quenching. In this paper, we have comprehensively investigated the relationship between the crystal structures, electronic structures, and also electronic and thermal transport properties of (Pb 1– x Sn x )S ( x = 0–1). It is experimentally confirmed that an equilibrium phase of layered GeS-type Sn-rich (Pb 1– x Sn x )S is a p-type semiconductor at x ≥ 0.7, whereas n-type conduction is observed at x = 0.5 and 0.6. In contrast, the stabilized nonequilibrium layered phase with 0.2 ≤ x ≤ 0.4 is an n-type semiconductor with the band gaps of 1.18–1.22 eV, and the electron density increases up to 6.4 × 10 17 cm –3 in (Pb 0.8 Sn 0.2 )S. Furthermore, the layered nonequilibrium phase exhibits an ultralow room-temperature thermal conductivity of 0.40–0.65 W/(mK), much lower than those of both end members, i.e., GeS-type SnS ( x = 1) and RS-type PbS ( x = 0). Based on first-principles electron and phonon transport calculations, layered n-type (Pb 0.75 Sn 0.25 )S potentially shows a high thermoelectric figure of-merit of 0.34 even at 300 K under an optimized electron concentration. The controllability of bipolar carrier polarity in layered (Pb 1– x Sn x )S alongside the low thermal conductivity is an advantageous characteristic for applications based on p–n homojunctions, such as photovoltaics and thermoelectrics.
Source: ACS Applied Electronic Materials
Authors: Mari Hiramatsu, Zhongxu Hu, Sakura Yoshikawa, Zan Yang, Xinyi He, Takayoshi Katase, Jun-ichi Yamaura, Hajime Sagayama, Terumasa Tadano, Shigenori Ueda, Hidenori Hiramatsu, Hideo Hosono, Toshio Kamiya
Institutions: Institute of Integrated Research, Institute of Science Tokyo, MDX Research Center for Element Strategy, High Energy Accelerator Research Organization, Institute of Materials Structure Science, The Institute for Solid State Physics, The University of Tokyo, National Institute for Materials Science, Materials & Structures Laboratory
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Awards: Construction of innovatively novel optical semiconductors based on the original chemical design concept, and evolution of their devices, G2451401391, Development and device demonstration of new ultra-widegap oxide semiconductors beyond the conventional design roule, Mixed-anion thermoelectric oxides: performance enhancement by thermal conductivity reduction and mechanistic insights, G4137340833, Exploration of angular momentum current science and its application to spin-orbit electronics, 層状化合物の非平衡相境界を利用した構造転移の誘起と巨大熱伝導変調, オキシカルコゲナイドの欠陥学理の構築とワイドギャップ半導体の設計・開拓への展開, Building a theory of chemical doping in wide-gap semiconductors and exploring new materials
OpenAlex ID: W4404192400