基于Simmons模型的THz-STM隧穿电流特性分析 |
投稿时间:2024-12-24 修订日期:2025-01-08 点此下载全文 |
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基金项目:国家自然科学基金(12064028)、江西省自然科学(20232BAB201045)和南昌航空大学研究生创新专项(YC2024-059)的支持。 |
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中文摘要:利用超短太赫兹脉冲耦合到隧道扫描显微镜技术中可以使得该技术具有超强的时空分辨成像能力,从而在材料表面成像、性能诊断和检测等方面发挥更大的作用。基于Simmons模型分析了太赫兹隧道扫描显微技术的工作原理和影响隧穿电流的因素,结合数值计算详细研究了太赫兹脉冲参数和样品功函数等对势垒和隧穿电流的影响,特别是太赫兹脉冲脉宽、相位和样品功函数等与隧穿电流的关系,并对其物理机制进行了讨论。研究发现隧穿电流是太赫兹脉冲相位的周期性函数;太赫兹电场与直流偏置电场诱导产生隧穿电流存在临界值,该临界值由材料功函数决定,耦合电场大于该值后隧穿电流是太赫兹电场的线性函数;当太赫兹脉冲脉宽增加,则隧穿电流整流电子数目振荡式下降并趋于稳定。本文对深入理解太赫兹隧道扫描显微技术微观物理机制、指导相关实验有很好的参考价值。 |
中文关键词:太赫兹 隧道扫描显微 近场 Simmons模型:隧穿电流 |
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Analysis of properties of tunneling current in the THz-STM based on the Simmons model |
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Abstract:The coupling of ultrashort terahertz (THz) pulses into the scanning tunneling microscope (STM) technology can make this technology with high spatial-temporal resolution, so as to play a greater role in material surface imaging, performance diagnosis and testing. Based on Simmons model, the principle of THz-STM is introduced and the factors affecting the tunneling current are analyzed. The influence of THz pulse and work function of samples on the potential barrier and tunneling current are studied in detail with numerical calculations. Particularly, the relationships between THz pulse (including its duration and phase), work function of samples, and threshold of tunneling current are discussed. It is found that the tunneling current is the period function of the phase of THz pulse. There is a threshold for the coupling of the THz and DC field, which is related to the material work function. The tunneling current is the linear function of the THz field above this threshold. It will decrease with an oscillation state and then tread to stable when the duration of the THz pulse increases. This work will help understand the mechanism of THz-STM experimental setup and might offer a reference for the related experiments. |
keywords:terahertz scanning tunneling microscopy near-field Simmons model tunneling current |
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