论文标题
激子光谱和固定在六角硼硝酸盐中的mose2-wse2外侧异质结构中的扩散
Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral heterostructures encapsulated in hexagonal boron nitride
论文作者
论文摘要
化学蒸气沉积（CVD）允许过渡金属二甲基元素异质结构的横向边缘外观以及在光电子中的潜在应用。对载体和激子运输至关重要的是构成单层的两种材料的质量以及侧向异质结的性质。由于光学转变的不均匀扩展，光学特性的重要细节在成长的异质结构样品中无法访问。在这里，我们在T = 4 K和300 K处进行光谱，以访问CVD种植的Mose2-We2侧面异质结构中的光学光谱，这些跃迁从生长基层转移并封装在HBN中。光致发光（PL），反射率对比度和拉曼光谱显示出相当狭窄的光学过渡线宽，类似于高质量的去角质单层。在高分辨率透射电子显微镜（HRTEM）中，我们发现共价键合的Mose2-We2典型的近距离连接，典型的3nm范围。在PL成像实验中，我们发现WSE2的有效激发扩散长度比在低t = 4 K时长的Mose2更长，而在300 K时，此趋势被逆转。
Chemical vapor deposition (CVD) allows lateral edge epitaxy of transition metal dichalcogenide heterostructures with potential applications in optoelectronics. Critical for carrier and exciton transport is the quality of the two materials that constitute the monolayer and the nature of the lateral heterojunction. Important details of the optical properties were inaccessible in as-grown heterostructure samples due to large inhomogeneous broadening of the optical transitions. Here we perform optical spectroscopy at T = 4 K and also at 300 K to access the optical transitions in CVD grown MoSe2-WSe2 lateral heterostructures that are transferred from the growth-substrate and are encapsulated in hBN. Photoluminescence (PL), reflectance contrast and Raman spectroscopy reveal considerably narrowed optical transition linewidth similar to high quality exfoliated monolayers. In high-resolution transmission electron microscopy (HRTEM) we find near-atomically sharp junctions with a typical extent of 3nm for the covalently bonded MoSe2-WSe2. In PL imaging experiments we find effective excitonic diffusion length that are longer for WSe2 than for MoSe2 at low T=4 K, whereas at 300 K this trend is reversed.
