亚10 nm超薄金属薄膜的光电特性及应用研究进展

A Review on Sub-10 nm Ultrathin Metal Films

摘要:

亚10 nm超薄金属膜具有高透光性、低电阻、高机械柔性及低成本等优点，是一种理想的光电材料。相比于常规厚度的金属薄膜，亚10 nm超薄金属膜具有更优异的光电特性，在太阳能电池、平板显示、色彩装饰、可穿戴电子设备、智能窗户等领域有广阔的应用前景。亚10 nm超薄金属膜的制备质量直接决定了光电特性。由于金属普遍具有较大的表面能，因此润湿性较差。在亚10 nm极端厚度下通过直接沉积的方式难以形成连续、长程有序且均匀的薄膜，而生长过程中产生的缺陷必然会导致出现电阻增大、光学性质不稳定等问题，从而影响光电器件的性能。如何制备高纯度、高质量的亚10 nm超薄金属膜及相关应用的研究，已成为光电器件领域的研究热点，面临着极大的挑战。首先，阐述了超薄金属膜的光电特性和力学特性，并结合薄膜生长机制，对近几年开发的超薄金属膜高质量制备方法（如引入种子层、掺杂共溅射、表面修饰、低温沉积、离子束抛光、聚合物辅助光化学沉积等）进行了总结和对比。然后，从实际应用需求角度出发，对亚10 nm超薄金属膜在透明电极、结构色滤光片、太阳能吸收器、Low-E涂层及等离子器件中的设计方法及应用形式进行了归纳，指出亚10 nm超薄金属薄膜研究所面临的挑战。最后，对其发展前景进行了展望。

Abstract:

Due to their advantages of high light transmittance， low resistance， high mechanical flexibility and low cost， ultrathin metal films with a thickness of sub-10 nm has been seen as ideal optoelectronic materials. Compared with metal films of conventional thickness， sub-10 nm ultrathin metal films have better optoelectronic properties and wider application possibilities， and are widely used in solar cells， flat panel displays， color decoration， wearable electronic devices， smart windows， and other fields. The preparation quality of sub-10 nm ultrathin metal films directly determines their optoelectronic features. Due to the poor wettability， it is difficult for metal to form a continuous， long range and uniform film by direct deposition at an extreme thickness of sub-10 nm. The resultant defects will inevitably lead to problems such as increased resistance and unstable optical properties， affecting the performance of optoelectronic devices. Therefore， fabricating high-purity， high-quality sub-10 nm thick ultrathin metal films and carrying out their application has become the research hotspot. Based on recent publications， this review systematically summarizes the recent progress in sub-10 nm thick ultrathin metal films. This review first describes the optoelectronic and mechanical properties of sub-10 nm metal films. Then the growth mechanism and high-quality material preparation methods of ultrathin metal films including introducing a seed layer， doping co-sputtering， surface modification， cryogenic deposition， ion-beam polishing and the polymer-assisted photochemical deposition are reviewed. Furthermore， from the perspective of applications， this review summarizes the design approaches and applications forms of sub-10 nm thick metal films in applications of transparent conductors， structural color filters， solar absorber， Low-E coatings and plasmas devices. Finally， the development trend and applications of sub-10 nm thick ultrathin metal films are prospected.