Single electron transistor based charge sensors: fabrication challenges and opportunities

Measuring electric charge precisely is crucial in various fields including semiconductor device fabrication, particle physics, materials science, medical imaging, electrotherapy, electroplating, and electrolysis. It becomes even more demanding for quantum applications. Existing technology like voltmeters and electrometers are valuable tools, but limitations like low sensitivity, drift, and accessibility hinder their use in quantum applications. Researchers are addressing these issues by exploring new approaches like nanomaterial-based sensors with quantum mechanics for ultra-sensitive charge detection. The single-electron transistor (SET) achieves high sensitivity by controlling individual electron flow due to the Coulomb blockade principle and other quantum phenomena. Existing charge sensors have limited operation, as it is very challenging to detect very small changes in charge due to the continuous current flow. In contrast, SETs control the flow of individual electrons due to the discrete nature of flowing electrons. Furthermore, ultra-low power and highly reliable electronic components can be created by precisely controlling single electrons, which introduces a new era of miniaturized and energy-efficient electronics. In this review, the rudiments of SETs and the significance of material choice for a SET are highlighted. The nano-fabrication methods, leading to the development of next-generation ultra-sensitive and low-power quantum electronics are pointed out. The challenges and issues are incorporated into developing new ideas, approaches, and technologies for the field of quantum sensors. Finally, we discuss the future outlook and potential developments to accelerate the development of high-precision SET-based charge sensors for future research directions.