透過垂直磁異向性電極探測二維過渡金屬二硫化物中自旋極化能谷載子

Detecting Spin-polarized Valley Carriers in Two-dimensional Transition Metal Dichalcogenides through Perpendicular Magnetic Anisotropic Electrodes

朱庭慶(Ting-Ching Chu)

指導教授 ： 林敏聰

國立臺灣大學/理學院/物理學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801709

摘要

能谷電子學，是一個結合了能谷以及電子學的詞彙，旨在控制在第一布里元區中帶有數個能谷的特定半導體的能谷自由度。額外的能谷自由度能夠和電子自旋的自由度結合，進而實現能夠對未來產業界有所貢獻的，以能谷為基礎應用的電子自旋元件。在各式各樣的半導體中，二維過渡金屬二硫化物是製作以能谷為基礎應用的電子自旋元件的候選材料。層狀結構的二維過渡金屬二硫化物的倒晶格為蜂巢狀，有著兩組三簡併態的能谷來提供電子額外的能谷自由度。此材料中的自由載子耦合的電子自旋與能谷極化狀態使我們容易控制它們的電子自旋自由度。

在此論文中，我們嘗試透過垂直磁異向性電極探測二維過渡金屬二硫化物中自旋極化的能谷載子。我們提供了在二氧化矽/矽基板上以化學氣相沉積成長單層二硫化鉬以及以機械剝離製備單層二硒化鎢的方法。我們透過電子槍熱蒸鍍方式成長鈀/鈷層狀薄膜，透過濺鍍方式成長鉑/鈷層狀薄膜，並且量測了它們的磁性性質。我們旋即製備了以垂直異向性電極為基礎的能谷電子裝置，並且探討它們的性質。

關鍵字

能谷電子學 ； 二硫化鉬 ； 二硒化鎢 ； 化學氣相沉積 ； 晶體剝離 ； 垂直磁異向性

並列摘要

Valleyronics, which is a terminology combines valley and electronics, aims to control over the valley degree of freedom in certain semiconductors that possess multiple valleys inside the first Brillouin zone. This extra valley degree of freedom can be combined with electron spin degree of freedom in the system to realize valley-based Spintronic devices that may contribute further applications into industries in the near future. Among various kind of semiconductors, Two-dimensional transition metal dichalcogenides(TMDCs) are candidate materials for valley-based Spintronic devices. The reciprocal lattice of layered 2D-TMDCs are in a honeycomb shape with two set of three-fold valleys, providing electrons an extra valley degree of freedom. Coupled spin and valley polarization of free carriers in the materials facile us to control their spin degree of freedom.

In this thesis, we try to detect spin polarized valley carriers in 2D-TMDCs through perpendicular magnetic anisotropy electrodes. Preparation method of monolayer molybdenum disulfide(MoS$_2$) by chemical vapour deposition(CVD) and monolayer tungsten diselenide(WSe$_2$) by mechanical exfoliation onto SiO$_2$/Si substrates are given. Pd/Co and Pt/Co thin film layered structures are grown by e-gun evaporation or sputtering respectively, and their magnetic properties are measured. PMA based valleytronic devices are subsequently fabricated and their properties are dicussed.

並列關鍵字

Valleytronics ； molybdenum disulfide ； tungsten diselenide ； chemical vapour deposition ； crystal exfoliation ； perpendicular magnetic anisotropy

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