Study of van der Waals heterostructure-based PN junction for electronics and optoelectronic applications

Abstract

The present technological requirements have urged researchers to explore the world of 2D materials. The extraordinary capabilities and multi-functional characteristics exhibited by these layered materials have gained interest ever since graphene was isolated. Extensive studies have been completed which have introduced many groups of 2D materials including elemental 2D materials, transition metal dichalcogenides (TMDC), mono-chalcogenides (MC), oxides etc. The heterostructures stacks of these layered materials held together by weak van der Waals forces result in novel properties for electronic and optoelectronic devices. We fabricated and characterized a p-type GeAs and n-type InSe based vdW heterostructure junction in this work. The fabrication was completed through the deterministic dry transfer of mechanically cleaved InSe and GeAs on pre-patterned gold electrodes. Annealing of the devices allowed smooth contact at the junction and resulted in enhanced charge transport. A rectification ratio ranging between 10 – 105 was calculated at zero back gate voltage and Vd = +2/-2. The devices were examined for photovoltaic characteristics, the junction was illuminated with a wavelength of 532 etam with increasing power levels (0.1 microW - 100 microW), and the responsivity was found to be 6.4 AW-1. Photocurrent maps and IV plots were also acquired and analyzed.