Development of wafer-scale nanowire transfer method with various temperature thermal treatment for high-performance flexible devices

Abstract

The development of high performance flexible electronic devices has attracted con-siderable attention owing to the proliferation of flexible/wearable future electronic appli-cations. Nanowires (NWs) are a promising candidate for high performance flexible devices because of their extraordinary physical/chemical properties based on a unique nanoscale 1D form-factor. To achieve high device performance and diverse applications, it is im-portant to control the aspect-ratio, crystallinity, composition, and defect density of NWs with wide range of material-selection on flexible substrates. In addition, recent applica-tions of NWs, including high performance nano-devices require a reliable method to fabri-cate fully-aligned and dense NWs over a large area. However, it is still challenging to fab-ricate geometry-controlled and high quality NWs, regardless of materials, on a large area flexible substrate, limiting NWs for the wide range of applications. Here, we develop a novel transfer method to fabricate fully-aligned, dense, ultralong NWs, regardless of ma-terials, on a flexible substrate. To achieve our purpose, we newly develop a top-down ap-proach fabrication based nano-transfer methods based on high-temperature thermal treatment and novel sacrificial layer techniques. The thermal temperature annealing is classified with 3 ranges, which can be used for material property modification of wide range of materials, such as metals, semiconductors, and ceramics

i) low-temperature cov-ering from room temperature to 200 °C, ii) mid-temperature range covering about 400 °C, and iii) high-temperature range for about 700 °C. Using these method, we first produce an ultralong, perfectly aligned metal / semiconductor nanowire array that is heat treated at >700 °C on a flexible polyethylene terephthalate substrate. Based on the devel-oped methods, we further developed various advanced nano-electronic devices, such as flexible heater and wearable nanogenerator, with high simplicity and manufacturing reliability.