Source/Drain extension doping is crucial for minimizing the series resistance of the ungated channel and reducing the contact resistance of field‐effect transistors (FETs) in complementary metal–oxide–semiconductor (CMOS) technology. 2D semiconductors, such as MoS2 and WSe2, are promising channel materials for beyond‐silicon CMOS. A key challenge is to achieve extension doping for 2D monolayer FETs without damaging the atomically thin material. This work demonstrates extension doping with low‐resistance contacts for monolayer WSe2 p‐FETs. Self‐limiting oxidation transforms a bilayer WSe2 into a hetero‐bilayer of a high‐work‐function WOxSey on a monolayer WSe2. Then, damage‐free nanolithography defines an undoped nano‐channel, preserving the high on‐current of WOxSey‐doped FETs while significantly improving their on/off ratio. The insertion of an amorphous WOxSey interlayer under the contacts achieves record‐low contact resistances for monolayer WSe2 over a hole density range of 1012 to 1013 cm−2 (1.2 ± 0.3 kΩ µm at 1013 cm−2). The WOxSey‐doped extension exhibits a sheet resistance as low as 10 ± 1 kΩ □−1. Monolayer WSe2 p‐FETs with sub‐50 nm channel lengths reach a maximum drain current of 154 µA µm−1 with an on/off ratio of 107–108. These results define strategies for nanometer‐scale selective‐area doping in 2D FETs and other 2D architectures.

中文翻译：

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用于 P 型单层 WSe2 场效应晶体管的低电阻触点的延伸掺杂


在互补金属氧化物半导体 （CMOS） 技术中，源极/漏极扩展掺杂对于最小化非受干扰通道的串联电阻和降低场效应晶体管 （FET） 的接触电阻至关重要。MoS2 和 WSe2 等 2D 半导体是硅外 CMOS 的有前途的通道材料。一个关键挑战是在不损坏原子薄材料的情况下实现 2D 单层 FET 的延伸掺杂。这项工作展示了单层 WSe2 p-FET 的低电阻触点的延伸掺杂。自限性氧化将双层 WSe2 转化为单层 WSe2 上高功功能 WOxSey 的异质双层。然后，无损伤纳米光刻定义了一个未掺杂的纳米通道，保留了 WOxSey 掺杂 FET 的高导通电流，同时显著提高了它们的开/关比。在触点下插入非晶态 WOxSey 夹层，在 1012 至 1013 cm-2 的孔密度范围内实现了单层 WSe2 创纪录的低接触电阻（1013 cm-2 处为 1.2 ± 0.3 kΩ μm）。WOxSey 掺杂延伸件表现出低至 10 ± 1 kΩ □−1 的薄层电阻。具有亚 50 nm 通道长度的单层 WSe2 p-FET 的最大漏极电流为 154 μA μm−1，开/关比为 107–108。这些结果定义了 2D FET 和其他 2D 架构中纳米级选择性区域掺杂的策略。