  Two-dimensional transition metal dichalcogenides (TMDCs) have properties
attractive for optoelectronic and quantum applications. A crucial element for
devices is the metal-semiconductor interface. However, high contact resistances
have hindered progress. Quantum transport studies are scant as low-quality
contacts are intractable at cryogenic temperatures. Here, temperature-dependent
transfer length measurements are performed on chemical vapour deposition grown
single-layer and bilayer WS$_2$ devices with indium alloy contacts. The devices
exhibit low contact resistances and Schottky barrier heights (\sim10
k$\Omega$\si{\micro\metre} at 3 K and 1.7 meV). Efficient carrier injection
enables high carrier mobilities ($\sim$190 cm$^2$V$^{-1}$s$^{-1}$) and
observation of resonant tunnelling. Density functional theory calculations
provide insights into quantum transport and properties of the WS$_2$-indium
interface. Our results reveal significant advances towards high-performance
WS$_2$ devices using indium alloy contacts.
