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中国物理学会期刊

铌掺杂锆钛酸铅铁电薄膜调控CuInS2量子点的阻变性能

CSTR: 32037.14.aps.71.20220911

Resistive properties of CuInS2 quantum dots regulated by niobium-doped lead zirconate titanate ferroelectric films

CSTR: 32037.14.aps.71.20220911
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  • CuInS2量子点 (quantum dots, QDs)具有宽尺寸调节范围 (2—20 nm)、丰富的电子俘获位点、高光吸收系数、较高的载流子迁移率和制备工艺简单等优势, 可应用于下一代非易失性存储器, 但其开关电压(–4.5/4.5 V)和阻变开关比 (103)还达不到实际使用要求. 本文引入铌掺杂锆钛酸铅 (Nb:Pb(Zr0.52Ti0.48)O3, PNZT)制备CuInS2 QDs/PNZT复合薄膜, 发现PNZT的引入可以明显改善QDs的阻变性能, 开关电压降至–4.1/3.4 V, 阻变开关比提升至106, 在103次的循环耐久性测试中始终保持良好的稳定性. 切换PNZT薄膜的铁电极化方向可以改变CuInS2 QDs/PNZT复合薄膜界面势垒高度和耗尽区宽度, 以此调控CuInS2 QDs/PNZT复合薄膜的阻变性能.

     

    As a new type of non-volatile memory, quantum dot resistive random access memory (RRAM) has attracted much attention for its easy preparation, fast responding time, high storage density, and smaller device size. CuInS2 quantum dot (CuInS2 QD) is a kind of excellent resistive functional material with abundant electron capture sites, high optical absorption coefficient, and high carrier mobility. In this work, CuInS2 QDs/Nb:Pb (Zr0.52Ti0.48)O3 (PNZT) films are prepared by spin-coating CuInS2 QDs on PNZT films. The results show that the resistive properties of CuInS2 QDs RRAMs can be effectively improved by introducing PNZT films and can be controlled by changing the polarization direction. The CuInS2 QDs/PNZT film in the negative polarization state promotes the interfacial electrons to enter into the PNZT film, which will reduce the height of the interfacial barrier and the thickness of the interfacial depletion region. And it will reduce the resistance of the composite film at the low resistance state (LRS). Compared with the switching voltage and resistive switching ratio of the pure CuInS2 QDs film (103), the switching voltage of the device decreases to –4.1/3.4 V and the resistive switching ratio increases to 106. Furthermore, it maintains good stability in the 103 cycle durability test. In contrast, the CuInS2 QDs/PNZT film interface has a larger barrier height and depletion-layer thickness when the PNZT is in the positive polarization state, which increases the resistance of the composite film in the LRS state. As a result, the switching voltage of the device increases to –6.4/5.7 V with a resistive switching ratio of 104. The resistive properties of the CuInS2 QDs/PNZT film can be tuned by changing the polarization direction, as the polarization direction of the PNZT changes the interfacial energy band structure and affects the conduction mechanism. This work reveals the feasibility of using ferroelectric thin films to improve the resistive properties of quantum dots RRAMs and thus providing an approach to further developing RRAMs.

     

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