  With the development of quantum technology, hybrid devices that combine
superconductors (S) and semiconductors (Sm) have attracted great attention due
to the possibility of engineering structures that benefit from the integration
of the properties of both materials. However, until now, none of the
experiments have reported good control of band alignment at the interface,
which determines the strength of S-Sm coupling and the proximitized
superconducting gap. Here, we fabricate hybrid devices in a generic way with
argon milling to modify the interface while maintaining its high quality.
First, after the milling the atomically connected S-Sm interfaces appear,
resulting in a large induced gap, as well as the ballistic transport revealed
by the multiple Andreev reflections and quantized above-gap conductance
plateaus. Second, by comparing transport measurement with Schr\"odinger-Poisson
(SP) calculations, we demonstrate that argon milling is capable of varying the
band bending strength in the semiconducting wire as the electrons tend to
accumulate on the etched surface for longer milling time. Finally, we perform
nonlocal measurements on advanced devices to demonstrate the coexistence and
tunability of crossed Andreev reflection (CAR) and elastic co-tunneling (ECT)
-- key ingredients for building the prototype setup for realization of Kitaev
chain and quantum entanglement probing. Such a versatile method, compatible
with the standard fabrication process and accompanied by the well-controlled
modification of the interface, will definitely boost the creation of more
sophisticated hybrid devices for exploring physics in solid-state systems.
