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看见“能带弯曲”的间接证据：NiO/Si异质结构筑与太赫兹时域光电导验证——推荐一个物理化学实验

游雨杭1, 李勇1, 李傲1, 张凡1,2, 金兵1, 李有勇3   

  1. 1 山东大学化学与化工学院, 前沿化学研究院, 山东 青岛 266237;
    2 山东大学计算机科学与技术学院, 山东 青岛 266237;
    3 苏州大学功能纳米与软物质研究院, 江苏 苏州 215123
  • 收稿日期:2026-01-22 录用日期:2026-03-26
  • 通讯作者: 金兵, 李有勇 E-mail:jinbing@sdu.edu.cn;yyli@suda.edu.cn Bing Jin, Youyong Li
  • 基金资助:
    国家重点研发计划(2025YFE0121800,2022YFA1503101)；国家自然科学基金(92580104)；苏州市科技发展计划——医疗应用基础研究项目(SKY2023040)；澳门特别行政区科学技术发展基金(0030/2022/AGJ)；苏州纳米科学技术协同创新中心；江苏省高等学校优势学科建设工程(PAPD)；“111计划”；碳基功能材料与器件国际联合研究实验室

Seeing the indirect signature of “band bending”: construction of a NiO/Si heterojunction and verification via terahertz time-domain photoconductivity–a recommended physical chemistry experiment

Yuhang You1, Yong Li1, Ao Li1, Fan Zhang1,2, Bing Jin1, Youyong Li3   

  1. 1 Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao 266237, Shandong Province, China;
    2 School of Computer Science and Technology, Shandong University, Qingdao 266237, Shandong Province, China;
    3 Institute of Functional Nano and Soft Materials, Soochow University, Suzhou 215123, Jiangsu Province, China
  • Received:2026-01-22 Accepted:2026-03-26
  • Contact: Bing Jin, Youyong Li E-mail:jinbing@sdu.edu.cn;yyli@suda.edu.cn

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摘要： 半导体异质结界面的能带弯曲与内建电场是实现光-电及光-化学能量转化的关键基础，也是化学与材料相关专业高年级在“能带-界面电场-载流子动力学”交叉内容教学中的重点与难点。本文设计了一个面向高年级本科生的物理化学实验：采用旋涂-退火工艺在高阻抗n型Si基底上制备NiO薄膜以构筑NiO/Si异质结，并在532 nm连续光照与暗态条件下利用太赫兹时域光谱(THz-TDS)非接触原位测量光生电导引起的太赫兹透过率变化。通过设置裸蓝宝石(C0)、NiO/蓝宝石(C1)、裸Si(S0)与NiO/Si (S1)等对照组，并结合退火温度与膜厚等工艺变量，建立“工艺-界面-载流子动力学-谱学信号”的证据链闭环。结果表明：在相同泵浦条件下，S1的太赫兹调制深度显著高于S0，而C1在相同泵浦下几乎无响应，说明界面效应可显著增强Si的稳态光生电导；该现象与异质结内建电场促进载流子分离/积累的能带弯曲效应一致，可作为课堂中“从光电导增强推断能带弯曲”的间接谱学证据与定量教学判据”。该实验将薄膜制备、半导体能带理论与太赫兹谱学数据处理贯通，可用于训练学生的动手操作、数据分析与对照推理能力。

关键词: 物理化学实验, 能带弯曲, 异质结, 太赫兹时域光谱

Abstract: Band bending and built-in electric fields at semiconductor heterojunction interfaces are fundamental to photoelectric and photochemical energy conversion, serving as key teaching points in advanced undergraduate courses that integrate band theory, interface electric fields, and carrier dynamics. This study designs a physical chemistry experiment for senior undergraduates: NiO thin films are fabricated on high-resistance n-type Si substrates via spin-coating and annealing to construct NiO/Si heterojunctions, followed by non-contact in situ measurements of terahertz transmission changes induced by photoconductivity using terahertz time-domain spectroscopy (THz-TDS) under 532 nm continuous-wave illumination. Control groups including bare sapphire (C0), NiO/sapphire (C1), bare Si(S0), and NiO/Si(S1) are established, alongside process variables such as annealing temperature and film thickness, to form a closed-loop evidence chain linking fabrication processes, interface properties, carrier dynamics, and spectroscopic signals. Results demonstrate that S1 exhibits significantly greater terahertz modulation depth than S0 under identical pumping conditions, while C1 shows negligible response, indicating that interfacial effects substantially enhance the steady-state photoconductivity of Si. This phenomenon aligns with band bending-induced carrier separation/accumulation at heterojunctions, providing indirect spectroscopic evidence and a quantitative teaching metric for “inferring band bending from photoconductivity enhancement”. The experiment integrates thin-film fabrication, semiconductor band theory, and terahertz spectroscopic data analysis, training students in hands-on skills, data interpretation, and controlled experimental reasoning.

Key words: Physical chemistry experiment, Band bending, Heterojunction, Terahertz time-domain spectroscopy