Tailoring the morphological, optical, luminescence, and gas sensing properties of SILAR-grown ZnO thin films: an impact of adsorption time

IF 4.2 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Optical Materials Pub Date : 2025-09-26 DOI:10.1016/j.optmat.2025.117567

Mohd Shkir , Mohd Taukeer Khan , R. Marnadu , Aslam Khan , Farhat S. Khan , Thamraa Alshahrani

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Abstract

Controlling thin film growth parameters is critical for tailoring the functional properties of metal oxide semiconductors. This study investigate the influence of adsorption time during the successive ionic layer adsorption and reaction (SILAR) process on the structural, optical, photophysical, and ammonia (NH₃) gas sensing properties of zinc oxide (ZnO) thin films. Precursor immersion time was systematically varied (5–20 s) to engineer microstructure and enhance device performance. Structural analysis via X-ray diffraction (XRD) and Raman spectroscopy showed that increasing adsorption time promotes crystallinity, enlarges crystallite size (from 16.56 to 27.88 nm), and reduces microstrain and defect density. Field-emission scanning electron microscopy (FESEM) revealed a morphological evolution from granular clusters to vertically aligned nanorods, increasing active surface area. Optical absorption spectra demonstrated a redshift in the band edge and a narrowing of the optical bandgap from 3.10 to 2.50 eV due to sub-bandgap defect states. Steady-state and time-resolved fluorescence spectra indicate enhanced radiative recombination and shorter carrier lifetimes, with the 20 s sample showing a lifetime of 548 ps. Notably, the 15 s film achieved outstanding NH₃ sensing performance, with rapid response (5.7 s), fast recovery (10.1 s), high selectivity, and humidity tolerance over 50 days. This work demonstrates that adsorption time in SILAR cycles can be systematically tuned to control ZnO film morphology, defect states, and photophysical dynamics. The optimized 15 s condition delivers record-high NH₃ response (5270 at 50 ppm) with long-term stability, establishing adsorption time as a simple yet powerful parameter for reproducible, high-performance ZnO gas sensors.

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silar生长ZnO薄膜的形态、光学、发光和气敏特性：吸附时间的影响

控制薄膜生长参数对调整金属氧化物半导体的功能特性至关重要。研究了连续离子层吸附反应（SILAR）过程中吸附时间对氧化锌（ZnO）薄膜结构、光学、光物理和氨（NH3）气敏性能的影响。系统地改变前驱体浸泡时间（5-20 s），以设计微结构并提高器件性能。x射线衍射（XRD）和拉曼光谱的结构分析表明，增加吸附时间可以促进结晶度，增大晶粒尺寸（从16.56 nm增大到27.88 nm），降低微应变和缺陷密度。场发射扫描电镜（FESEM）显示了从颗粒簇到垂直排列的纳米棒的形态演变，增加了活性表面积。由于子带隙缺陷态的存在，光学吸收光谱显示出带边缘的红移和带隙从3.10 eV缩小到2.50 eV。稳态和时间分辨荧光光谱表明，辐射重组增强，载流子寿命缩短，20 s样品的寿命为548 ps。值得注意的是，15 s薄膜具有出色的NH3传感性能，具有快速响应（5.7 s），快速恢复（10.1 s），高选择性和超过50天的耐湿性。这项工作表明，可以系统地调整SILAR循环中的吸附时间来控制ZnO薄膜的形态，缺陷状态和光物理动力学。优化后的15 s条件提供了创纪录的高NH3响应（50 ppm时5270），并且具有长期稳定性，将吸附时间作为可重复的高性能ZnO气体传感器的简单而强大的参数。

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来源期刊

Optical Materials 工程技术-材料科学：综合

CiteScore

6.60

自引率

12.80%

发文量

1265

审稿时长

38 days

期刊介绍： Optical Materials has an open access mirror journal Optical Materials: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. The purpose of Optical Materials is to provide a means of communication and technology transfer between researchers who are interested in materials for potential device applications. The journal publishes original papers and review articles on the design, synthesis, characterisation and applications of optical materials. OPTICAL MATERIALS focuses on: • Optical Properties of Material Systems; • The Materials Aspects of Optical Phenomena; • The Materials Aspects of Devices and Applications. Authors can submit separate research elements describing their data to Data in Brief and methods to Methods X.