Impacts of interface contaminations on the MoS₂ field effect transistors and a modified fabrication process to pursue a better interface quality

The interface of the two-dimensional (2D) material plays a crucial role in the properties of the material itself. When 2D materials are used as a channel for electrical devices, negative influence from surface contaminations during the fabrication process should be avoided to ensure device performance and reliability. In this article, the impacts as well as the mechanisms of the interface contaminations on the molybdenum disulfide (MoS₂) field effect transistors were studied. An effective method using an atomic layer deposition (ALD) grown Al₂O₃ dielectric layer to reduce exposure time of MoS₂ during processing was introduced. Combined with the annealing process, the fabricated MoS₂ field effect transistors with a Al₂O₃ protective layer demonstrate a high On/Off current ratio of 5 × 10⁷, and a hysteresis of 80 mV in terms of decent reliability. A sulfur repair mechanism on the MoS₂/Al₂O₃ interface during annealing is revealed to explain the enhancement of the devices performance. This method can also be adopted in other 2D materials, paving the way for the next generation flexible electronics application. (paper)