  Two-dimensional (2D) materials have garnered significant attention in recent
years due to their atomically thin structure and unique electronic and
optoelectronic properties. To harness their full potential for applications in
next-generation electronics and photonics, precise control over the dielectric
environment surrounding the 2D material is critical. The lack of nucleation
sites on 2D surfaces to form thin, uniform dielectric layers often leads to
interfacial defects that degrade the device performance, posing a major
roadblock in the realization of 2D-based devices. Here, we demonstrate a
wafer-scale, low-temperature process (< 250 {\deg}C) using atomic layer
deposition (ALD) for the synthesis of uniform, conformal amorphous boron
nitride (aBN) thin films. ALD deposition temperatures between 125 and 250
{\deg}C result in stoichiometric films with high oxidative stability, yielding
a dielectric strength of 8.2 MV/cm. Utilizing a seed-free ALD approach, we form
uniform aBN dielectric layers on 2D surfaces and fabricate multiple quantum
well structures of aBN/MoS2 and aBN-encapsulated double-gated monolayer (ML)
MoS2 field-effect transistors to evaluate the impact of aBN dielectric
environment on MoS2 optoelectronic and electronic properties. Our work in
scalable aBN dielectric integration paves a way towards realizing the
theoretical performance of 2D materials for next-generation electronics.
