| AVS 65th International Symposium & Exhibition | |
| 2D Materials Focus Topic | Tuesday Sessions |
| Session 2D+EM+MI+MN+NS-TuA |
| Session: | 2D Device Physics and Applications |
| Presenter: | Quinten Yurek, University of California, Riverside |
| Authors: | Q. Yurek, University of California, Riverside I. Liao, University of California, Riverside D. Barroso, University of California, Riverside A.E. Nguyen, University of California, Riverside N. Duong, University of California, Riverside G. Stecklein, University of California, Riverside L. Bartels, University of California, Riverside |
| Correspondent: | Click to Email |
As device dimensions shrink, surfaces and interfaces between materials make up a larger volume fraction of a device leading to degrading device properties in 3D materials. One solution is to use 2D materials, however these materials introduce additional challenges. For instance, high resistance Schottky barriers and a small number of free charge carriers in comparison to bulk materials. The effective mobility of field effect transistors (FETs) based on two-dimensional (2D) single-layer transition metal dichalcogenide (TMD) films is frequently limited by barriers at the contacts, as opposed to the native properties of the TMD material. Specifically, high resistance Schottky barriers form at the TMD/metal interface because of the film’s thinness and resulting small number of carriers. Here we demonstrate a scalable single-step deposition method for nanoscale hybrid 2D/3D TMD structures encoded by lithographic patterning prior to deposition. By confining the metal contact to the bulk regions of WSe2, the effective mobility is increased to nearly 100 cm2V-1s-1 with an on/off ratio >105 for bottom-gated devices (through 300nm of oxide), even for comparatively long channels (>5 microns) and absent other contact optimization. Our process involves lithographic patterning of a hafnium (IV) dioxide film onto the SiO2/Si substrate prior to TMD growth. Bulk-like 3D WSe2 is observed to grow at the location of the hafnia, while 2D single-layer material is grown in regions of bare SiO2. Systematic evaluation of transport data allows us to extract Schottky barrier heights and other fundamental properties of our hybrid devices. We demonstrate that this process can be used to create devices with metal/3D TMD contacts, which exhibit a reduced Schottky barrier height, while continuing to use 2D TMD channels, which result in an excellent on-off ratio.