Controllable Heterogeneous Nucleation for Patterning High‐Quality Vertical and Horizontal ZnO Microstructures toward Photodetectors

Abstract High‐quality crystalline micro‐ and nanostructures based on inorganic semiconductors including zinc oxide (ZnO) have attracted considerable interest in electronic and optoelectronic applications due to their outstanding properties. ZnO micro‐ and nanocrystals can be fabricated by the moderate and high throughput hydrothermal synthesis. Yet it is restricted by patterning large‐area ZnO crystals with high‐quality and programmable geometries through the hydrothermal process for the optoelectronic integration. Here, a capillary‐bridge manipulation approach is demonstrated to control the dewetting process of ZnO precursor solution for patterning precursor arrays. Based on precursor arrays, vertically aligned high‐quality ZnO microrod arrays with homogeneous morphology and pure crystallographic orientation are fabricated via a hydrothermal epitaxial method. Statistical results and crystallization theories guide the experimental optimization and discussion of the crystallization mechanism, dominated by the competition between homogeneous nucleation and heterogeneous nucleation. High‐quality ZnO microbelt arrays are achieved through a surfactant‐mediated hydrothermal method after ZnO microrod arrays are transferred to a polydimethylsiloxane substrate. Photodetectors based on ZnO microbelts exhibit a high responsivity of 2.3 × 10⁴ A W⁻¹, a light on–off ratio exceeding 10⁵, and stable recyclability. It is anticipated that this work provides new insights into patterning inorganic high‐quality micro‐ and nanostructures for multi‐functional integrated devices.