Guided Organic Crystalline Nanowires by Directional Friction‐Transferred Poly(Tetrafluoroethylene) Nanogrooves and Their Monolithic Phototransistors

Abstract

AbstractThe monolithic integration of bottom‐up nanowires into devices requires rational growth of aligned nanowires. Of the proposed aligned growth methods, few are sufficiently general to be applicable to diverse materials and substrates. In this work, oriented poly(tetrafluoroethylene) (PTFE) grooves with nanoscale depth and width are transferred onto different substrates through a simple directional mechanical friction. This friction is achieved in a few seconds by a program‐driven handwriting machine. Various organic molecules (e.g., Alq3, NiPc, CoPc, CuPc, F16CuPc) are therefore assembled into oriented crystalline nanowires on the surface of Si, Si/SiO2, and glass. The self‐alignment of these nanowires enables a scalable device fabrication directly on growth substrates, eliminating structural damage and contamination during post‐growth alignment. For example, using the aligned F16CuPc nanowires on PTFE‐coated Si/SiO2 wafers, back‐gate field‐effect phototransistors are fabricated in a scalable manner by directly depositing an array of micro‐sized electrodes. Statistical results show that these phototransistors operate in n‐type enhancement mode with thresholds of a few volts. In addition, they exhibit fast photoresponse on the order of tens of milliseconds and long‐term stability in the vis–NIR spectrum. The generality of this guided nanowire growth and resulting monolithic devices offer new opportunities for the monolithic integration of nanowire‐based devices.