Electrolyte‐Gated Vertical Transistor Charge Transport Enables Photo‐Switching

• Published in: Advanced electronic materials Vol. 10; no. 6
• Main Authors: Vieira, Douglas Henrique, Nogueira, Gabriel Leonardo, Merces, Leandro, Bufon, Carlos César Bof, Alves, Neri
• Format: Journal Article
• Language: English
• Published: Wiley-VCH 01.06.2024
• Subjects: charge transport mechanism; electrolyte‐gated transistor; Schottky diode; spray pyrolysis; vertical phototransistor
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202300562

Proposals for new architectures that shorten the length of the transistor channel without the need for high‐end techniques are the focus of very recent breakthrough research. Although vertical and electrolyte‐gate transistors are previously developed separately, recent advances have introduced electrolytes into vertical transistors, resulting in electrolyte‐gated vertical field‐effect transistors (EGVFETs), which feature lower power consumption and higher capacitance. Here, EGVFETs are employed to study the charge transport mechanism of spray‐pyrolyzed zinc oxide (ZnO) films to develop a new photosensitive switch concept. The EGVFET's diode cell revealed a current‐voltage relationship arising from space‐charge‐limited current (SCLC), whereas its capacitor cell provided the field‐effect role in charge accumulation in the device's source perforations. The findings elucidate how the field effect causes a continuous shift in SCLC regimes, impacting the switching dynamics of the transistor. It is found ultraviolet light may mimic the field effect, i.e., a pioneering demonstration of current switching as a function of irradiance in an EGVFET. The research provides valuable insights into the charge transport characterization of spray‐pyrolyzed ZnO‐based transistors, paving the way for future nano‐ and optoelectronic applications. ZnO‐based transistors have been fabricated in an innovative configuration combining vertical architecture with electrolyte usage. The diode counterpart reveals a current‐voltage relationship arising from space‐charge limited current, while its capacitor counterpart plays the role in charge accumulation. Beyond the transport mechanism, the findings demonstrate excellence in their application, showcasing current switching based on irradiance—a phenomenon analogous to the field effect.