Effect of Chromium Adhesion Layer Thickness on Contact Resistance and Schottky Barrier Characteristics in WSe2 Field-Effect Transistor.

While metal adhesion layers are commonly used in the fabrication of field-effect transistors (FETs) based on two-dimensional (2D) materials, the impact of adhesion layer thickness on device performance remains insufficiently explored. In this study, we systematically investigate how the thickness of a Cr adhesion layer influences the contact resistance and Schottky barrier characteristics of multilayer WSe₂ FETs. Contact resistance results, extracted via the transfer length method for Cr thicknesses of 1 nm, 4 nm, and 7 nm, reveal that thicker Cr layers (4 nm and 7 nm) result in significantly lower resistance (<200 kΩ·μm) compared to the much higher resistance (6.6 MΩ·μm) observed with 1 nm Cr thickness. Temperature-dependent transport measurements and Arrhenius analysis further indicate a reduction in Schottky barrier height with increasing Cr thickness, implying improved carrier injection. These results specifically demonstrate how the commonly used Cr adhesion layer thicknesses of at least 4 nm increase the electrical performance of WSe₂-based devices.