Nanocatalysis has received considerable attention in the scientific community due to their superior reactivity compared to their macro-sized counterparts. MEMS nanoreactors allow scientists to view these reactions in-situ. This opens up doors to finally understanding the underlying mechanisms of the nanocatalyst's effectiveness, which may eventually improve our every day lives. This thesis focuses on the viewing port of the device -- the electron-transparent window (ETW) -- and how they can be improved for future generations. From scattering theory, it was determined that the best way to improve the imaging quality of current ETWs was to develop thinner ones. Two questions were then asked: can a thinner ETW be integrated into a nanoreactor process? If so, how will it affect the mechanical strength of the ETW? Aluminum oxide (alumina) was chosen specifically because of its deposition method, atomic layer deposition (ALD). The characteristics and material properties of ALD alumina were assessed and it was determined that they are suitable for ETW applications. Using ALD alumina presented a few challenges in its integration into nanoreactors, especially the use of vapor hydrogen fluoride. ALD alumina ETWs were able to be successfully integrated into a nanoreactor down to 5 nm thick. The 5 nm alumina ETWs are able to withstand a pressure difference at least 0.75 bar, however they were not able to survive inside a TEM as they disintegrated immediately under the electron beam. Alumina ETWs that are 10 nm were able to be imaged in a TEM. These windows were tested in a transmission electron microscope (TEM) and scanning electron microscope (SEM) to showcase the improved electron-transparency. The ultra-thin ALD alumina ETWs can improve the imaging quality of nanoreactors, due to their lower thickness compare to current nanoreactors. The successful release of 5 nm membranes may also be useful for other applications, such as sensors.