Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2
Copper Vacancies and Heavy Holes in the Two-Dimensional Semiconductor KCu3–xSe2
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DOI：
10.1021/acs.chemmater.7b02117
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发表时间：
2017-07
影响因子：
8.6
通讯作者：
A. Rettie;Mihai I. Sturza;C. Malliakas;A. Botana;D. Chung;M. Kanatzidis
中科院分区：
文献类型：
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作者：
A. Rettie;Mihai I. Sturza;C. Malliakas;A. Botana;D. Chung;M. Kanatzidis
二维材料 KCu3-xSe2 是使用 K2Se3 助熔剂直接从元素合成的。它以 CsAg3S2 结构结晶（单斜空间群 C2/m，a = 15.417(3) A、b = 4.0742(8) A、c = 8.3190(17) A 和 β = 112.94(3)°），单晶细化揭示了由 K+ 分隔的无限缺铜 [Cu3–xSe2]− 层离子。热分析表明 KCu3–xSe2 在~755 °C 下同成分熔化。紫外可见光谱显示光学带隙约为 1.35 eV，这在本质上是直接的，正如电子结构计算所证实的那样。单晶上的电子传输测量在 300 K 时产生了~6 × 10-1 Ω cm 的面内电阻率，具有复杂的温度依赖性。塞贝克系数测量结果与掺杂 p 型半导体（300 K 时 S = +214 μV K–1）一致，掺杂归因于铜空位。传输主要是由相对平坦的价带引起的低迁移率（大约 1 cm2 V–1 s–1）空穴......
The two-dimensional material KCu3–xSe2 was synthesized using both a K2Se3 flux and directly from the elements. It crystallizes in the CsAg3S2 structure (monoclinic space group C2/m with a = 15.417(3) A, b = 4.0742(8) A, c = 8.3190(17) A, and β = 112.94(3)°), and single-crystal refinement revealed infinite copper-deficient [Cu3–xSe2]− layers separated by K+ ions. Thermal analysis indicated that KCu3–xSe2 melts congruently at ∼755 °C. UV–vis spectroscopy showed an optical band gap of ∼1.35 eV that is direct in nature, as confirmed by electronic structure calculations. Electronic transport measurements on single crystals yielded an in-plane resistivity of ∼6 × 10–1 Ω cm at 300 K that has a complex temperature dependence. The results of Seebeck coefficient measurements were consistent with a doped p-type semiconductor (S = +214 μV K–1 at 300 K), with doping being attributed to copper vacancies. Transport is dominated by low-mobility (on the order of 1 cm2 V–1 s–1) holes caused by relatively flat valence bands...