  Due to Fermi level pinning (FLP), metal-semiconductor contact interfaces
result in a Schottky barrier height (SBH), which is usually difficult to tune.
This makes it challenging to efficiently inject both electrons and holes using
the same metal - an essential requirement for several applications, including
light-emitting devices and complementary logic. Interestingly, modulating the
SBH in the Schottky-Mott limit of de-pinned van der Waals (vdW) contacts
becomes possible. However, accurate extraction of the SBH is essential to
exploit such contacts to their full potential. In this work, we propose a
simple technique to accurately estimate the SBH at the vdW contact interfaces
by circumventing several ambiguities associated with SBH extraction. Using this
technique on several vdW contacts, including metallic 2H-TaSe$_2$,
semi-metallic graphene, and degenerately doped semiconducting SnSe$_2$, we
demonstrate that vdW contacts exhibit a universal de-pinned nature. Superior
ambipolar carrier injection properties of vdW contacts are demonstrated (with
Au contact as a reference) in two applications, namely, (a) pulsed
electroluminescence from monolayer WS$_2$ using few-layer graphene (FLG)
contact, and (b) efficient carrier injection to WS$_2$ and WSe$_2$ channels in
both nFET and pFET modes using 2H-TaSe$_2$ contact.
