Temperature-Dependent and Gate-Tunable Rectification in a Black Phosphorus/WS₂ van der Waals Heterojunction Diode

Heterostructures comprising two-dimensional (2D) semiconductors fabricated by individual stacking exhibit interesting characteristics owing to their 2D nature and atomically sharp interface. As an emerging 2D material, black phosphorus (BP) nanosheets have drawn much attention because of their small band gap semiconductor characteristics along with high mobility. Stacking structures composed of p-type BP and n-type transition metal dichalcogenides can produce an atomically sharp interface with van der Waals interaction which leads to p–n diode functionality. In this study, for the first time, we fabricated a heterojunction p–n diode composed of BP and WS2. The rectification effects are examined for monolayer, bilayer, trilayer, and multilayer WS2 flakes in our BP/WS2 van der Waals heterojunction diodes and also verified by density function theory calculations. We report superior functionalities as compared to other van der Waals heterojunction, such as efficient gate-dependent static rectification of 2.6 × 104, temperature dependence, thickness dependence of rectification, and ideality factor of the device. The temperature dependence of Zener breakdown voltage and avalanche breakdown voltage were analyzed in the same device. Additionally, superior optoelectronic characteristics such as photoresponsivity of 500 mA/W and external quantum efficiency of 103% are achieved in the BP/WS2 van der Waals p–n diode, which is unprecedented for BP/transition metal dichalcogenides heterostructures. The BP/WS2 van der Waals p–n diodes have a profound potential to fabricate rectifiers, solar cells, and photovoltaic diodes in 2D semiconductor electronics and optoelectronics.