Se-Vacancy Healing with Substitutional Oxygen in WSe for High-Mobility p-Type Field-Effect Transistors.

Transition-metal dichalcogenides possess high carrier mobility and can be scaled to sub-nanometer dimensions, making them viable alternative to Si electronics. WSe is capable of hole and electron carrier transport, making it a key component in CMOS logic circuits. However, since the p-type electrical performance of the WSe-field effect transistor (FET) is still limited, various approaches are being investigated to circumvent this issue. Here, we formed a heterostructural multilayer WSe channel and solution-processed aluminum-doped zinc oxide (AZO) for compositional modification of WSe to obtain a device with excellent electrical properties. Supplying oxygen anions from AZO to the WSe channel eliminated subgap states through Se-deficiency healing, resulting in improved transport capacity. Se vacancies are known to cause mobility degradation due to scattering, which is mitigated through ionic compensation. Consequently, the hole mobility can reach high values, with a maximum of approximately 100 cm/V s. Further, the transport behavior of the oxygen-doped WSe-FET is systematically analyzed using density functional theory simulations and photoexcited charge collection spectroscopy measurements.