Layer-engineered I-V characteristics of p-Si/WS2 Van der Waals Heterostructure diode

Single crystals of WS2 were exfoliated micromechanically and transferred layer by layer on top of a p-Si wafer, forming a heterogeneous junction diode at the interface of p-Si/WS2. The forward and reverse biasing of the diode operates satisfactorily with an increasing turn on voltage as the layer thickness decreases. We further found that the value of the ideality factor improves up to 1.6 after exfoliation and there is a 98% increase in the diode rectification ratio compared to the un-exfoliated crystal. The band gap tuning with thickness by the simple method of mechanical exfoliation and transferring makes them inexpensive, and multifunctional bulk-like devices hold the promise for integration of WS2 layers with Si-based electronics to develop highly efficient optoelectronic devices.