Study of photo-induced atomic processes on semiconductor surfaces by means of femtosecond spectroscopy

利用飞秒光谱研究半导体表面光致原子过程

• 批准号: 09440115
• 负责人: TANIMURA Katsumi
• 金额: $ 8.96万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440115/
• 关键词: reconstructed surface; desorption; photo-induced structural changes; STM; femtosecond spectroscopy; 細構成表面

The purpose of this project is to make clear the microscopic processes of laser-induced electronic instability on clean semiconductor surfaces. The surfaces of Si(111)-(7x7) and InP(110)-(1x1) in an UHY chamber were excited either by fs-laser pulses for dynamical study or by ns- laser pulses for spectroscopy. Structural changes induced were studied by direct imaging of the atomic structures by scanning tunneling microscope (STM) and by high-sensitive detection of desorbed neutral species. Main results obtained in this project are summarized below.1) On Si(111)-(7x7), which is a proto-typical example of reconstructed semiconductor surfaces, laser-induced electronic instability is induced by the surface-specific electronic transition at 2.0 eV, followed by non-linear localization to induce bond breaking of adatoms on the surface. Two-hole localization followed by the phonon-kick process has been proposed to be the origin of the instability.2) On InP(110)-(1x1), which shows quasi-one dime … More nsional atomic and electronic properties, similar laser-induced electronic instability is induced, but with strongly wavelength-dependent morphologies in structural changes. Upon exciting surface specific transitions, P-vacancy strings are generated along [110] direction, while two-dimensional vacancy islands are developed upon bulk-electronic excitation. These characteristics can be ascribed to different properties of photo-generated excited species in surface states and in bulk electronic states ; the former shows one-dimensional nature, while the latter is isotropic in mobility.3) For studying desorption induced as a result of surface-structural changes, we successfully developed a new method of femtosecond non-resonant ionization spectroscopy (FNRIS) for detecting several neutral species simultaneously with high sensitivity. This method was applied for InP surfaces to show that desorption processes are also strongly super-linear with respect to the excitation intensity, similarly to the case of vacancy formation on the surface. Also, primary product of desorption has been confirmed to be monoatomic P and In atoms for clean (1x1) surface, being consistent with STM observation. Our results obtained in this project is the first demonstration of FNRIS to be a powerful tool for studying desorption from compound semiconductor surfaces. Less

该项目的目的是弄清楚激光在干净的半导体表面上引起的电子不稳定性的微观过程。 UHY 室中的 Si(111)-(7x7) 和 InP(110)-(1x1) 表面通过用于动力学研究的飞秒激光脉冲或用于光谱学的纳秒激光脉冲激发。通过扫描隧道显微镜（STM）对原子结构进行直接成像并通过高灵敏度检测解吸的中性物质来研究引起的结构变化。本项目取得的主要成果总结如下。 1) 在 Si(111)-(7x7) 上，这是重构半导体表面的典型例子，激光诱导的电子不稳定性是由 2.0 eV 的表面特定电子跃迁引起的，随后是非线性局域化，导致表面吸附原子的键断裂。声子踢过程之后的两孔局域化被认为是不稳定性的根源。2) 在 InP(110)-(1x1) 上，它表现出准一角原子和电子特性，引发了类似的激光诱导电子不稳定性，但在结构变化中具有强烈的波长依赖性形态。在激发表面特定跃迁时，沿[110]方向生成P-空位串，而在体电子激发时形成二维空位岛。这些特性可归因于光生激发态物质在表面态和体电子态下的不同特性；前者表现出一维性质，而后者则具有各向同性的迁移率。3）为了研究表面结构变化引起的解吸，我们成功开发了一种新的飞秒非共振电离光谱（FNRIS）方法，可以高灵敏度同时检测多种中性物质。该方法应用于 InP 表面，表明解吸过程对于激发强度也是强超线性的，类似于表面空位形成的情况。此外，解吸的主要产物已被证实是单原子 P 和 In 原子，清洁 (1x1) 表面，与 STM 观察一致。我们在该项目中获得的结果首次证明 FNRIS 是研究化合物半导体表面解吸的强大工具。较少的

项目成果

J.Kanasaki: "Translational energy distribution of Si atoms desorved by laser-induced bond breaking of adatoms on Si(111)" Physical Review Letters. 82. 644-647 (1999)

J.Kanasaki：“激光诱导 Si(111) 上吸附原子键断裂所解构的 Si 原子的平移能量分布”物理评论快报。

金崎順一、谷村克巳: "半導体表面構造の光誘起変化と構成原子の脱離"固体物理. 34. 657-668 (1999)

Junichi Kanazaki、Katsumi Tanimura：“半导体表面结构的光致变化和组成原子的分离”固体物理 34. 657-668 (1999)。

J. Kanasaki, T, Ishida, K. Ishikawa, and K. Tanimura: "Laser-induced electronic bond breaking and desorption of Si adatoms on Si(111)-(7x7)"Phys.Rev.Lett.. 80-18. 4080-4083 (1998)

J. Kanasaki、T、Ishida、K. Ishikawa 和 K. Tanimura：“Si(111)-(7x7) 上 Si 吸附原子的激光诱导电子键断裂和解吸”Phys.Rev.Lett.. 80-18。

K.Tanimura and J.Kanasaki: "Laser-Induced Bond Breaking and Structural Changes on Si(111)-7x7 Surfaces"Applied Surface Science. 127-129. 33-39 (1998)

K.Tanimura 和 J.Kanasaki：“Si(111)-7x7 表面上的激光诱导键断裂和结构变化”应用表面科学。

J.Kanasaki, N.Mikasa, and K.Tanimura: "Laser-Induced Electronic Desorption from InP Surfaces Studied by the Femtosecond Non-resonant Ionization Spectroscopy"Physical Review B. (to be published).

J.Kanasaki、N.Mikasa 和 K.Tanimura：“通过飞秒非共振电离光谱研究 InP 表面的激光诱导电子解吸”物理评论 B.（待出版）。