Nonequilibrium Rock-Salt-Type Pb-Doped SnSe with High Carrier Mobilities ≈ 300 cm2/(Vs)

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• 作者：Takeshi Inoue ; Hidenori Hiramatsu ; Hideo Hosono ; Toshio Kamiya
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 12, 2016
• 年：2016
• 卷：28
• 期：7
• 页码：2278-2286
• 全文大小：577K
• 年卷期：0
• ISSN：1520-5002

文摘

We synthesized nonequilibrium cubic rock-salt (RS)-type (Sn,Pb)Se and investigated their optoelectronic properties with the expectation that the RS-type structure would exhibit better carrier transport properties than the equilibrium GeS-type layered crystal structure in SnSe because the RS-type structure has the three-dimensional network of (PbSe₆) octahedra, while the GeS-type structure has the two-dimensional network of (SnSe₃), leading to larger band dispersions and smaller carrier effective masses. To stabilize the nonequilibrium phase, epitaxial thin films were grown by a unique method, a reactive solid-phase epitaxy with a thin RS-type PbSe epitaxial template layer. Additionally, a rapid quenching process from 600 °C to room temperature was also effective for stabilizing the nonequilibrium RS-type (Sn,Pb)Se epitaxial films. We succeeded in controlling Pb concentration continuously from 0 to 100% in the (Sn,Pb)Se solid-solution films. The minimum Pb concentration to stabilize the RS-type SnSe was extended from the previously reported value of 63% to 50%. A band gap bowing effect was observed with the smallest estimated band gap of ∼0.14 eV for the RS-type (Sn_0.35Pb_0.65)Se. The GeS-type to RS-type structural change increased hole mobility drastically from 60 for SnSe to 290 cm²/(Vs) for 58% Pb-doped RS-type (Sn,Pb)Se film as expected. It was found that p-type to n-type conversion occurs by further higher Pb concentrations ≥61%, and the highest electron mobility of 340 cm²/(Vs) was observed.