Chemical Vapor Deposition Growth of Monolayer WSe2 with Tunable Device Characteristics and Growth Mechanism Study
Chemical Vapor Deposition Growth of Monolayer WSe2 with Tunable Device Characteristics and Growth Mechanism Study
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DOI：
10.1021/acsnano.5b01301
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发表时间：
2015-06-01
期刊：
影响因子：
17.1
通讯作者：
Zhou, Chongwu
中科院分区：
文献类型：
--
作者：
Liu, Bilu;Fathi, Mohammad;Zhou, Chongwu
过渡金属二硫属化合物（TMDCs）半导体材料由于其独特的电学、光学和力学性能，近年来引起了人们的广泛关注。在大量的TMDC中，二硒化钨（WSe 2）单层是特别感兴趣的，因为它具有直接的带隙和可调的电荷传输行为，这使得它适合于各种电子和光电应用。直接合成单层大畴WSe 2及其生长机理的研究是实现WSe 2应用的重要步骤。在这里，我们报告系统的研究环境压力化学气相沉积（CVD）生长单层和几层WSe 2薄片直接在二氧化硅衬底上。使用光学显微镜、原子力显微镜、拉曼光谱和光致发光光谱对WSe 2薄片进行表征。我们研究了生长参数，重点是生长温度和持续时间，影响的大小，层数，和形状的生长WSe2薄片。我们还表明，CVD生长的单层WSe 2，类似于机械剥离的样品的传输特性，可以调整到p型或annbipolar的电气行为，这取决于金属接触的类型。这些结果加深了我们对WSe_2气相生长机理的理解，对这些CVD生长单层材料在电子学和光电子学中的应用有一定的参考价值。
Semiconducting transition metal dichalcogenides (TMDCs) have attracted a lot of attention recently, because of their interesting electronic, optical, and mechanical properties. Among large numbers of TMDCs, monolayer of tungsten diselenides (WSe2) is of particular interest since it possesses a direct band gap and tunable charge transport behaviors, which make it suitable for a variety of electronic and optoelectronic applications. Direct synthesis of large domains of monolayer WSe2 and their growth mechanism studies are important steps toward applications of WSe2. Here, we report systematical studies on ambient pressure chemical vapor deposition (CVD) growth of monolayer and few layer WSe2 flakes directly on silica substrates. The WSe2 flakes were characterized using optical microscopy, atomic force microscopy, Raman spectroscopy, and photoluminescence spectroscopy. We investigated how growth parameters, with emphases on growth temperatures and durations, affect the sizes, layer numbers, and shapes of as-grown WSe2 flakes. We also demonstrated that transport properties of CVD-grown monolayer WSe2, similar to mechanically exfoliated samples, can be tuned into either p-type or annbipolar electrical behavior, depending on the types of metal contacts. These results deepen our understandings on the vapor phase growth mechanism of WSe2, and may benefit the uses of these CVD-grown monolayer materials in electronic and optoelectronics.