Ultrafast carrier dynamics in Si(111)7x7 dangling bonds probed by time-resolved second-harmonic generation and two-photon photoemission

被引：35

作者：

Mauerer, M. ^{[1
]}

Shumay, I. L.

Berthold, W.

Hoefer, U.

机构：

[1] Max Planck Inst Quantum Opt, D-85740 Garching, Germany

[2] Univ Marburg, Fachbereich Phys, D-35032 Marburg, Germany

[3] Univ Marburg, Zentrum Materialwissensch, D-35032 Marburg, Germany

来源：

PHYSICAL REVIEW B | 2006年 / 73卷 / 24期

关键词：

D O I：

10.1103/PhysRevB.73.245305

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

By combining time-resolved two-photon photoemission (2PPE) and optical second-harmonic generation (SHG), the dynamics of surface electronic states of Si(111)7x7 has been studied. In the experiment the normally unoccupied part of the adatom dangling-bond bands are populated by 1.55 eV pump pulses. The 2PPE results show very fast relaxation within these bands with lifetimes ranging between 40 and 150 fs depending on energy relative to the Fermi level. The regime of high excitation densities was investigated by means of time-resolved SHG. With increasing pump fluence, we observed filling of the surface bands and a concomitant increase of the optical relaxation times from 0.5-2 ps. The results are interpreted in terms of electron-electron scattering within a two-dimensional metallic system that is isolated from the bulk semiconductor.

引用

页数：8

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