Investigation of 2D-material based devices with as-grown metal contacts

Many 2D transition metal dichalcogenides (TMD) materials are considered ideal candidates for optical and electronic devices however, high-quality consistent electrical contacting is challenging. We will describe a process for forming as-grown contacts to thin film TMDs and present measurements investigating the underlying growth mechanisms and contact properties. TMDs such as MoS₂ were fabricated using a chemical vapor deposition (CVD) process on substrates with existing transition metal contacts which serve as both source material and self-forming contacts to the TMD material. Optical characterization shows high quality material. Electrical characterization of as-grown MoS₂ based devices typically reveals a metal-semiconductor-metal (MSM) Schottky contact, however, with significant variation. To investigate this variability, we performed cross-sectional SEM imaging as well as deposited post-growth contacts using standard techniques on material with as-grown contacts to help isolate the underlying characteristics of the contacts. These results indicate a complex formation process often resulting in a potentially controllable thin metal-oxide layer. This understanding provides a path to tune the growth process to form consistent high-quality contacts in a scalable manner.