Hysteresis erasure in ZIF-8@ZnO nanorod array field-effect transistors through oxygen chemisorption-induced depolarization

Zeolitic imidazolate framework-8 (ZIF-8) is a versatile candidate for next-generation electronics owing to its adjustable lattice and physicochemical properties. However, the utilization of ZIF-8 for the fabrication of solid-state electronics and circuit components, such as field-effect transistors (FETs), has not been realized thus far, primarily due to ongoing debates surrounding its electrical properties. In this work, we fabricated n-type FETs using ZIF-8@ZnO nanorod arrays. A significant hysteresis behavior was observed. It was demonstrated that this hysteresis cannot be assigned to the well-established ferroelectric effect but rather to the polarization of ZIF-8, wherein the electric field of the gate aligns the dipole of 2-methylimidazole through molecular orientation rotation. It was clarified that the process of annealing in air can result in the chemisorption of oxygen on methylimidazole, leading to a limitation in the rotation of methylimidazole. This restriction ultimately causes the depolarization of ZIF-8, resulting in the erasure of hysteresis. This study unfolds the tunable hysteresis behavior of ZIF-8 and its sensibility to oxygen, thereby highlighting the potential applications of ZIF-8 in FETs, nonvolatile memories, and gas sensors.