Highly Efficient Planar Hot Electron Emitters Based on Ultrathin Pyrolyzed Polymer Films

Miniaturized integrated hot electron emitters are highly sought after for application in chemical analytics and field-applicable systems. Here, we present the use of ultrathin pyrolyzed polymer films (PPFs) as the gate electrode, enabling the fabrication of highly efficient planar hot electron emitters (PHEEs). The thickness of the PPF was observed to be roughly 1 nm across a full 4" wafer, approaching the monolayer limit. Conductivities of up to 3.5 × 10⁴ S/m at pyrolysis temperatures of only 900 °C were measured, representing a 2-fold increase compared to bulk values. This renders an easily accessible 2D material with high electron transparency. Thus, the PHEE exhibits very high transfer ratios of up to 31% and proves to be stable at high pressures over an extended period of time. Furthermore, the straightforward integration route of the PPF presented here comprises only two steps: photolithography and subsequent pyrolysis. The fabricated devices exhibit high uniformity in performance, with a transfer ratio standard deviation of 2.9% across a single wafer. Ultimately, the devices were fabricated exclusively with silicon dioxide on silicon in combination with carbon, which represents a sustainable fabrication approach with inert materials. It has been demonstrated that the PHEE can also operate in both nitrogen and air, illustrating the utility of these emitters for gas ionization and sensing.