Unprecedented High Efficiency of Porous Silicon-Based Electron Emitter Achieved Through Electrochemical Oxidation

The demand for efficient electron sources in vacuum microelectronics is rising as devices become smaller and more integrated. Post-oxidation is an efficient method for passivating porous silicon (PS) to enhance the field emission performance of the PS-based electron emitter. This study reveals that electrochemical oxidation (ECO) in constant-voltage (CV) mode promotes more efficient and uniform oxidation of the PS layer without generating any surface crevices, as compared to the constant-current (CC) mode. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$11~\mu $ </tex-math></inline-formula>m thick PS layer, oxidized by the CV mode at 50 V for 20 min, achieves an unprecedented emission efficiency of 16.8% at a bias voltage of 28 V, positioning it as a promising on-chip electron source for future applications.