Singh Dharmendra K, S G Praveen, Jayakumar Adithya, M N Suma, Kamble Vinayak B, Mitra J, Jaiswal-Nagar D
School of Physics, Indian Institute of Science Education and Research Thiruvanthapuram, Vithura, Thiruvananthapuram 695551, Kerala, India.
Phys Chem Chem Phys. 2020 Dec 16;22(47):27861-27872. doi: 10.1039/d0cp05508e.
This work reports a systematic study of the evolution of charge transport properties in granular ultra-thin films of palladium of thicknesses varying between 6 nm and 2 nm. While the films with thickness >4 nm exhibit metallic behaviour, that at 3 nm thickness undergoes a metal-insulator transition at 19.5 K. In contrast, the 2 nm thick film remained insulating at all temperatures, with transport following Mott's variable range hopping. At room temperature, while the thicker films exhibit resistance decrease upon H2 exposure, the insulating film showed an anomalous initial resistance increase before switching to a subsequent decrease. The nanostructure dependent transport and the ensuing H2 response is modeled on a percolation model, which also explores the relevance of film thickness as a macroscopic control parameter to engineer the desired system response in granular metal films.
这项工作报告了对厚度在6纳米至2纳米之间变化的钯颗粒超薄膜中电荷传输特性演变的系统研究。当厚度大于4纳米的薄膜表现出金属行为时，3纳米厚的薄膜在19.5 K时发生金属-绝缘体转变。相比之下，2纳米厚的薄膜在所有温度下都保持绝缘，其输运遵循莫特可变范围跳跃。在室温下，较厚的薄膜在暴露于氢气时电阻降低，而绝缘薄膜在切换到随后的降低之前显示出异常的初始电阻增加。基于渗流模型对纳米结构相关的输运及随之而来的氢气响应进行了建模，该模型还探讨了薄膜厚度作为宏观控制参数对设计颗粒金属薄膜中所需系统响应的相关性。
