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The carbon-based van der Waals (vdW) heterostructures with metal-semiconductor (M-S) junction have shown great potential for nanodevices and optoelectronic applications; however, the Schottky barrier at interface restricts the injection efficiency of charges. Here, we systematically investigate the effect of the electronic field and biaxial strain on the electronic properties and the Schottky barrier height (SBH) of the PC 3/graphene(G) and PC3H/G vdW heterostructures through first-principles calculations. The results show that the charge redistribution at interface leads to a shift of the Fermi level, which determines the contact type and height of the Schottky barrier. Moreover, the contact type could be tuned from p-type Schottky contact to Ohmic contact by electronic field or in-plane biaxial strain, thus obtaining highly efficient charge transfer. Most importantly, we demonstrate that hydrogenation of PC3 is an effective strategy to partly screen the external electronic field, whereas more sensitive to strain for inducing the contact type transform and SBH variation of the PC3 H/G heterostructure . This work provides a promising to design novel carbon-based nonmetal vdW heterostructures and explore their potential applications in electronic and optoelectronic devices .

One of the most fundamental and challenging tasks to achieve high-performance ultra-thin atomic field effect transistors (FETs) is to obtain very low or even zero Schottky barrier height (SBH) at source/drain contact. Here, we propose that heteroatom substitution is an effective strategy to tune the performance of two-dimensional materials-based FETs, which is demonstrated by systematically exploring the effects of Se substitution on the structural and electronic properties, and SBH of MoS x Se(2−x)/graphene (MoS x Se(2−x)/G) heterostructures using first-principles calculations. Our findings suggest that the type and height of Schottky barrier can be adjusted by varying Se concentration. The transformation from n-type Schottky barrier to p-type Schottky barrier can be realized when the Se concentration is greater than 25%. With the increase of Se concentration, a lower p-type Schottky barrier can be obtained at the interface to achieve efficient charge transfer. Moreover, the Schottky barrier of MoS x Se(2−x)/G heterostructures with different Se concentration would disappear as the external electric field exceeds certain values. These results would provide a direction in developing high-performance FETs involving heteroatom substitution layers as contact electrodes.