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| Author(s): |
Gabriel Leonardo Nogueira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Presidente Prudente. 2022-12-20. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências e Tecnologia. Presidente Prudente |
| Defense date: | 2022-08-10 |
| Advisor: | Neri Alves |
| Abstract | |
Nowadays, electrolyte-gated transistors (EGT) and Schottky barrier vertical field-effect transistors (SB-VFET) are better options for the development of printed electronics than conventional transistors. In particular, the use of a metal oxide semiconducting layer as zinc oxide (ZnO) stands out because of its high mobility and transparency integrated with the solution-processed advantages. Even though the publications on the above topics have faced a fast-growing, a vertical transistor composed of an electrolytic gate and an active layer based on an oxide semiconductor is still missing. Here, we report a low-cost vertical electrolyte transistor (EG-SB-VFET) using spray-deposited ZnO as the semiconductor. This approach enables a notable performance with a low-voltage transistor operation resulting from electrolytic character. Besides, the vertical structure circumvents the need for high-resolution microfabrication. The main goal demanded several steps, in which we studied different materials and developed three ZnO-based devices: Schottky diode, EGT, and the EG-SB-VFET. We evaluated the Schottky diodes based on the post-processing of the experimental current-voltage data by applying different analytical methods (Mikhelashvili, Werner and Cheung). We achieved a series resistance of ~200 Ω and a barrier height of ~0,75 eV for the ZnO/AgNW junction. We used the performance of the standard EGTs using ZnO by spray pyrolysis as the benchmark for the vertical architecture ones. The main parameters are field-effect mobility of ~11 cm2 V-1 s-1, a transconductance of ~2.4 mS and a subthreshold swing of ~0.13 V dec-1. For the EG-SB-VFET, we calculated the main figure-of-merit from the transfer curves, which are a current density of ~111 mA cm-2, a transconductance of ~4.7 mS and a subthreshold swing of ~0,22 V dec-1. By analyzing the current modulation on output curves, it is clear that we can control the electric behavior based on the bias connections once the same device can behave in a diode or a transistor mode. In conclusion, the achieved EG-SB-VFETs performance without high-resolution patterns is even better than the standard micrometric-sized EGT. Therefore, the EG-SB-VFET based on spray-deposited ZnO and AgNW layers is an innovative way to circumvent the challenges of conventional TFTs. (AU) | |
| FAPESP's process: | 18/02037-2 - Development of all-printed vertical field-effect transistor |
| Grantee: | Gabriel Leonardo Nogueira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |