Monolayer molybdenum disulfide (MoS ₂ ) is an attractive 2D material with a wide range of potential applications in the field of electronics and optoelectronics. To obtain the best performance, it is very necessary to grow large area single crystals of MoS ₂ (single domain) to avoid the effects of grain boundaries, but is exceptionally challenging to do this. Here, we report a novel method which we call out-diffusion vapor transport to grow large area single crystal monolayer MoS ₂ using an otherwise conventional chemical vapor deposition system. In this method, microchannels were created on the boat to significantly limit the region where MoOx vapor can react with S vapor to form crystals. This growth method resulted in triangular monolayer MoS ₂ single crystals up to ∼640 μm on a side grown on an oxidized silicon substrate, the largest crystals reported to date. Most of these crystals were multilayer at the center. This common feature has been identified in the literature as partially reduced transition metal oxide nucleates a second layer. We also achieved fully monolayer MoS ₂ single crystals up to ∼450 μm on a side, the largest demonstrated without the MoOx. Fabricated field effect transistors (FET) using MoS ₂ monolayer crystal as the active layer demonstrate a conventional n-type behavior, room-temperature mobility up to 45.5 cm ² V ⁻¹ s ⁻¹ and a maximum ON-Current (ION)/OFF-current (IOFF) ratio of 1.8 × 10 ⁷ . Raman and Photoluminescence results indicate that the as-grown large area monolayer crystals have high crystalline quality and uniformity with minimal defects, a finding that is consistent with the high electron mobility. This research work provides a superior technique to grow large-area high-quality single-crystal monolayer MoS ₂ without resorting to exotic equipment or techniques.

中文翻译：

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使用外扩散传输生长非常大的 MoS ₂单晶及其在场效应晶体管中的应用

单层二硫化钼 (MoS ₂ ) 是一种有吸引力的二维材料，在电子和光电子领域具有广泛的潜在应用。为了获得最佳性能，非常有必要生长大面积的 MoS ₂单晶 （单畴）以避免晶界的影响，但这样做极具挑战性。在这里，我们报告了一种新方法，我们称之为外扩散蒸汽传输，以使用传统的化学气相沉积系统来生长大面积单晶单层 MoS ₂。在这种方法中，在船上创建了微通道，以显着限制 MoOx 蒸气与 S 蒸气反应形成晶体的区域。这种生长方法导致三角形单层 MoS 在氧化硅衬底上生长的一侧最大约 640 μm 的₂个单晶，这是迄今为止报道的最大晶体。大多数这些晶体在中心是多层的。这一共同特征在文献中被确定为部分还原的过渡金属氧化物使第二层成核。我们还在一侧实现了高达 450 μm 的完全单层 MoS ₂单晶，这是在没有 MoOx 的情况下所展示的最大单晶。使用 MoS ₂单层晶体作为有源层的制造场效应晶体管 (FET) 表现出传统的 n 型行为、高达 45.5 cm ² V ^-1 s ^{-1 的}室温迁移率 和最大导通电流 (ION)/OFF -电流（IOFF）比为 1.8 × 10 ⁷ . 拉曼和光致发光结果表明，生长的大面积单层晶体具有高结晶质量和均匀性，缺陷最少，这一发现与高电子迁移率一致。这项研究工作提供了一种无需借助外来设备或技术即可生长大面积高质量单晶单层 MoS ₂的卓越 技术。