Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices
Uniform and ultrathin high-κ gate dielectrics for two-dimensional electronic devices
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用于二维电子器件的均匀超薄高π栅极电介质
DOI：
10.1038/s41928-019-0334-y
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发表时间：
2019-12-01
影响因子：
34.3
通讯作者：
Wang, Xinran
中科院分区：
文献类型：
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作者：
Li, Weisheng;Zhou, Jian;Wang, Xinran
二维半导体可以用作低功率晶体管的沟道材料，但事实证明，在这种材料上沉积高质量、超薄的高κ电介质具有挑战性。特别是，原子层沉积通常会导致不均匀的成核和岛屿形成，从而产生多孔介电层，特别是当等效氧化物厚度较小时，会出现电流泄漏。在这里，我们报道了使用单层分子晶体作为种子层在二维半导体上沉积高κ栅电介质的原子层。该方法可以在石墨烯、二硫化钼(MoS_2)和二硒化钨(WSe_2)衬底上生长当量氧化层厚度为1 nm的介质。与使用已有方法制备的介质相比，我们的介质表现出更低的粗糙度、界面态密度和漏电流，以及更好的击穿电场。利用这种技术，我们制作了工作在60 GHz的石墨烯射频晶体管，以及电源电压为0.8 V、亚阈值摆动到60 mV的MoS_2和WSe_2互补金属氧化物半导体晶体管 dec−1。我们还制作了沟道长度为20 nm的MoS_2晶体管，开关比超过107。使用单层分子晶体作为种子层，可以在石墨烯、二硫化钼和二硒化钨上沉积当量氧化层厚度仅为1 nm的氧化铟介质。
Two-dimensional semiconductors could be used as a channel material in low-power transistors, but the deposition of high-quality, ultrathin high-κ dielectrics on such materials has proved challenging. In particular, atomic layer deposition typically leads to non-uniform nucleation and island formation, creating a porous dielectric layer that suffers from current leakage, particularly when the equivalent oxide thickness is small. Here, we report the atomic layer deposition of high-κ gate dielectrics on two-dimensional semiconductors using a monolayer molecular crystal as a seeding layer. The approach can be used to grow dielectrics with an equivalent oxide thickness of 1 nm on graphene, molybdenum disulfide (MoS2) and tungsten diselenide (WSe2). Compared with dielectrics created using established methods, our dielectrics exhibit a reduced roughness, density of interface states and leakage current, as well as an improved breakdown field. With the technique, we fabricate graphene radio-frequency transistors that operate at 60 GHz, and MoS2 and WSe2 complementary metal–oxide–semiconductor transistors with a supply voltage of 0.8 V and subthreshold swing down to 60 mV dec−1. We also create MoS2 transistors with a channel length of 20 nm, which exhibit an on/off ratio of over 107.Using a monolayer molecular crystal as a seeding layer, hafnium oxide dielectrics with an equivalent oxide thickness of only 1 nm can be deposited on graphene, molybdenum disulfide and tungsten diselenide.