ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology , Castelldefels, Barcelona 08860, Spain.
Nano Lett. 2015 Nov 11;15(11):7307-13. doi: 10.1021/acs.nanolett.5b02559. Epub 2015 Nov 2.
Semiconducting, two-dimensional molybdenum disulfide (MoS2) is considered a promising new material for highly sensitive photodetection, because of its atomically thin profile and favorable bandgap. However, reported photodetectors to date show strong variation in performance due to the detrimental and uncontrollable effects of environmental adsorbates on devices due to large surface to volume ratio. Here, we report on highly stable and high-performance monolayer and bilayer MoS2 photodetectors encapsulated with atomic layer deposited hafnium oxide. The protected devices show enhanced electronic properties by isolating them from the ambience as strong n-type doping, vanishing hysteresis, and reduced device resistance. By controlling the gate voltage the responsivity and temporal response can be tuned by several orders of magnitude with R ∼ 10-10(4) A/W and t ∼ 10 ms to 10 s. At strong negative gate voltage, the detector is operated at higher speed and simultaneously exhibits a low-bound, record sensitivity of D* ≥ 7.7 × 10(11) Jones. Our results lead the way for future application of ultrathin, flexible, and high-performance MoS2 detectors and prompt for further investigation in encapsulated transition metal dichalcogenide optoelectronics.
半导体二维二硫化钼 (MoS2) 因其原子级薄的厚度和合适的能带隙，被认为是一种很有前途的高灵敏度光电探测器新材料。然而，迄今为止报道的光电探测器由于大的比表面积与体积比，环境吸附物对器件的有害和不可控影响，导致其性能存在很大差异。在这里，我们报告了用原子层沉积氧化铪封装的高稳定性和高性能单层和双层 MoS2 光电探测器。受保护的器件通过将其与环境隔离，表现出增强的电子性能，例如强 n 型掺杂、消失的迟滞和降低的器件电阻。通过控制栅极电压，可以将响应率和时间响应调节几个数量级，响应率 R ∼ 10-10(4) A/W，时间响应 t ∼ 10 ms 至 10 s。在强负栅极电压下，探测器以更高的速度运行，同时具有低截止频率，记录灵敏度 D* ≥ 7.7 × 10(11) Jones。我们的结果为未来超薄、灵活和高性能 MoS2 探测器的应用铺平了道路，并促使进一步研究封装的过渡金属二卤化物光电子学。
