Facile Fabrication of a Two-Dimensional TMD/Si Heterojunction Photodiode by Atmospheric-Pressure Plasma-Enhanced Chemical Vapor Deposition

Abstract

A growth technique to directly prepare two-dimensional (2D) materials onto conventional semiconductor substrates, enabling low-temperature, high-throughput, and large-area capability, is needed to realize competitive 2D transition-metal dichalcogenide (TMD)/three-dimensional (3D) semiconductor heterojunction devices. Therefore, we herein successfully developed an atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique, which could grow MoS2 and WS2 multilayers directly onto PET flexible substrate as well as 4-in. Si substrates at temperatures of <200 °C. The as-fabricated MoS2/Si and WS2/Si heterojunctions exhibited large and fast photocurrent responses under illumination of a green light. The measured photocurrent was linearly proportional to the laser power, indicating that trapping and detrapping of the photogenerated carriers at defect states could not significantly suppress the collection of photocarriers. All the results demonstrated that our AP-PECVD method could produce high-quality TMD/Si 2D–3D heterojunctions for optoelectronic applications.

Large area few-layer TMD film growths and their applications

“…However, the group noted that the plasma in the growth chamber tended to create surface defects on the synthesized material, necessitating further optimization to improve sample quality [64]. Kim et al optimized the technique further to allow atmospheric pressure PECVD growths of MoS 2 and WS 2 [65]. Growths were conducted at temperatures as low as 100 • C, yielding few layer 4-inch diameter growths of both TMDs on silicon as well as on flexible substrates [65].…”

“…Kim et al optimized the technique further to allow atmospheric pressure PECVD growths of MoS 2 and WS 2 [65]. Growths were conducted at temperatures as low as 100 • C, yielding few layer 4-inch diameter growths of both TMDs on silicon as well as on flexible substrates [65]. While domain sizes/mobilities were not measured, both TMDs produced large and fast photocurrent responses to incident laser excitation; these samples were of sufficient quality for optoelectronic applications [65].…”

“…Growths were conducted at temperatures as low as 100 • C, yielding few layer 4-inch diameter growths of both TMDs on silicon as well as on flexible substrates [65]. While domain sizes/mobilities were not measured, both TMDs produced large and fast photocurrent responses to incident laser excitation; these samples were of sufficient quality for optoelectronic applications [65]. PECVD technology to our knowledge has not yielded large area monolayer TMD growth (perhaps because of the plasma-induced surface defects making a single continuous layer currently infeasible).…”

Nonthermal Plasma-Enhanced Chemical Vapor Deposition of Two-Dimensional Molybdenum Disulfide

“…Plasma methods, on the other hand, have been effective at low-temperature deposition of MoS 2 but require long reaction times, 26 , 27 hazardous chemicals (H 2 S), 19 − 22 , 25 − 29 and tend to produce multilayer or rough films. 19 , 21 , 22 , 26 , 27 , 29 Typically, molybdenum (Mo) is predeposited onto a substrate, which is then exposed to a H 2 S plasma to produce multilayer MoS 2 at low temperatures. 27 , 29 These techniques tend to be the most effective for low-temperature synthesis of few-layer MoS 2 .…”

“… 19 , 21 , 22 , 26 , 27 , 29 Typically, molybdenum (Mo) is predeposited onto a substrate, which is then exposed to a H 2 S plasma to produce multilayer MoS 2 at low temperatures. 27 , 29 These techniques tend to be the most effective for low-temperature synthesis of few-layer MoS 2 . Sputtering techniques have been developed but produce multilayer and randomly oriented films.…”