While digital electronics has become entirely ubiquitous in today's world and appears in the limelight, analogue electronics is still playing a crucial role in many devices and applications. Current analogue circuits are mostly manufactured using silicon as active material, but the ever present demand for improved performance, new devices and flexible integration has -similar to their digital counterparts -pushed for research into alternative materials. In recent years two-dimensional materials have received considerable research interest, fitting their promising properties for future electronics. In this work we demonstrate an operational amplifier -a basic building block of analogue electronics -using a two-dimensional semiconductor, namely molybdenum disulfide, as active material. Our device is capable of stable operation with good performance, and we demonstrate its use in feedback circuits such as inverting amplifiers, integrators, log amplifiers, and transimpedance amplifiers.At a system level, electronic devices can be characterized as either analogue or digital. While digital electronics works by using strictly defined, discrete signal values -0 and 1 -in analogue electronics a signal can take any physically available level. Although the incredible increase in performance/price ratio of digital circuits has made many kinds of analogue circuits obsolete, there is still significant demand for analogue electronics in today's world.As with their digital counterparts, manufacturing of analogue electronics is still mostly done on silicon, but also here the never ceasing demand for higher performance, new kinds of devices and different, flexible integration is pushing research into new materials [1][2][3][4] . Two-

Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Costeffective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h-BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2") production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication.

graphene for the Al 2 O 3 ALD process. [30] Therefore, we conclude that the dielectric is not only pinhole-free, but also that the quality of the dielectric is not reduced due to the growth on top of a 2D material heterostructure.

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