Monolayer tungsten diselenide (1L-WSe₂) has been widely used for studying emergent physics due to the unique properties of its valence bands. However, electrical transport studies have been impeded by the lack of a reliable method to realize Ohmic hole-conducting contacts to 1L-WSe₂ especially at low carrier densities and low temperatures. Here, we report low-temperature p-type Ohmic contact to 1L-WSe₂ field-effect transistors at carrier densities (n) below n = 1 × 10¹² cm^–2 with negligible temperature dependence down to the lowest measured temperature (10 K). The non-rectifying barrier is achieved between 1L-WSe₂ and molybdenum trioxide (MoO₃), where 1L-WSe₂ underneath MoO₃ is heavily hole-doped through surface transfer doping. Electrical transport measurements reveal linear current–voltage relations at a temperature of 10 K and carrier densities from n = 7.7 × 10¹¹ cm^–2 to below the threshold. The finding is also supported by nearly temperature-independent output curves up to room temperature and a negligible contact barrier down to the subthreshold regime. Furthermore, the contact resistivity of MoO₃-contacted 1L-WSe₂ FET is 30.2–64.8 kΩ μm at n = 1.5 × 10¹² cm^–2, which is the lowest reported for 1L-WSe₂ FETs at such low carrier density. Realizing robust p-type Ohmic contact to a 2D transition metal dichalcogenide semiconductor will enable direct electronic measurements of quantum transport in correlated phases in the valence bands of monolayer semiconductors.

中文翻译：

---

使用高电子亲和力非晶 MoO3 与单层 WSe2 场效应晶体管的 P 型欧姆接触

单层二硒化钨(1L-WSe ₂ )因其价带的独特性质而被广泛用于研究涌现物理。然而，由于缺乏可靠的方法来实现与 1L-WSe ₂的欧姆空穴传导接触，尤其是在低载流子密度和低温下，电传输研究一直受到阻碍。在这里，我们报告了载流子密度 ( n ) 低于n = 1 × 10 ¹² cm ^{–2时与 1L-WSe} ₂场效应晶体管的低温 p 型欧姆接触，温度依赖性可忽略不计，直至最低测量温度 (10 K ). 非整流势垒在 1L-WSe _{2之间实现}和三氧化钼（MoO _{3 ），其中MoO 3}下面的1L-WSe ₂通过表面转移掺杂进行重度空穴掺杂。电传输测量揭示了 10 K 温度下的线性电流-电压关系和从n = 7.7 × 10 ¹¹ cm ^–2到低于阈值的载流子密度。这一发现也得到了高达室温的几乎与温度无关的输出曲线和低至亚阈值区域的可忽略不计的接触势垒的支持。此外，在n = 1.5 × 10 ¹² cm ^{–2时，MoO} ₃接触式 1L-WSe ₂ FET 的接触电阻率为 30.2–64.8 kΩ μm，这是 1L-WSe ₂ FET 在如此低的载流子密度下报道的最低值。实现与 2D 过渡金属二硫化物半导体的稳健 p 型欧姆接触将能够直接电子测量单层半导体价带中相关相的量子传输。