New Mechanism for Positronium Formation on a Silicon Surface

被引：32

作者：

Cassidy, D. B. ^{[1
]}

Hisakado, T. H. ^{[1
]}

Tom, H. W. K. ^{[1
]}

Mills, A. P., Jr. ^{[1
]}

机构：

[1] Univ Calif Riverside, Dept Phys & Astron, Riverside, CA 92521 USA

来源：

PHYSICAL REVIEW LETTERS | 2011年 / 106卷 / 13期

基金：

美国国家科学基金会;

关键词：

SLOW POSITRONS; VELOCITY; SPECTROSCOPY; DESORPTION; SI(100);

D O I：

10.1103/PhysRevLett.106.133401

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

We describe experiments in which positronium (Ps) is emitted from the surface of p-doped Si(100), following positron implantation. The observed emission rate is proportional to a Boltzmann factor exp{-E(A)/kT}, which is dependent on the temperature T of the sample and a characteristic energy E(A) = (0.253 +/- 0.004) eV. Surprisingly, however, the Ps emission energy has a constant value of similar to 0.16 eV, much greater than kT. This observation suggests the spontaneous emission of energetic Ps from a short-lived metastable state that becomes thermally accessible to available surface electrons once the positron is present. A likely candidate for this entity is an electron-positron state analogous to the surface exciton observed on p-Si(100) c(4 x 2) by Weinelt et al. [Phys. Rev. Lett. 92, 126801 (2004)].

引用

页数：4

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