A new metal transfer process for van der Waals contacts to vertical Schottky-junction transition metal dichalcogenide photovoltaics

• Published in: Science advances 2019-12, Vol.5 (12), p.eaax6061-eaax6061
• Main Authors: Went, Cora M, Wong, Joeson, Jahelka, Phillip R, Kelzenberg, Michael, Biswas, Souvik, Hunt, Matthew S, Carbone, Abigail, Atwater, Harry A
• Format: Article
• Language: English
• Subjects: Applied Physics; Engineering; MATERIALS SCIENCE; SciAdv r-articles; Science & Technology - Other Topics
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aax6061

Two-dimensional transition metal dichalcogenides are promising candidates for ultrathin optoelectronic devices due to their high absorption coefficients and intrinsically passivated surfaces. To maintain these near-perfect surfaces, recent research has focused on fabricating contacts that limit Fermi-level pinning at the metal-semiconductor interface. Here, we develop a new, simple procedure for transferring metal contacts that does not require aligned lithography. Using this technique, we fabricate vertical Schottky-junction WS solar cells, with Ag and Au as asymmetric work function contacts. Under laser illumination, we observe rectifying behavior and open-circuit voltage above 500 mV in devices with transferred contacts, in contrast to resistive behavior and open-circuit voltage below 15 mV in devices with evaporated contacts. One-sun measurements and device simulation results indicate that this metal transfer process could enable high specific power vertical Schottky-junction transition metal dichalcogenide photovoltaics, and we anticipate that this technique will lead to advances for two-dimensional devices more broadly.