Fraction of Positronium Formation at Semiconductor Surface

• Authors: S. Shrivastava , A. Upadhyay
• Languages of publication: EN

Abstracts

EN

The fraction of positronium formation (f_{ps}) has been calculated in Ge(110), Ge(111), Si(110) and Si(111) surfaces by solving the diffusion equation for positrons in semiconductors and by setting up the rate equation to describe the processes that are supposed to occur when a thermalised positron encounters the surface including the trapping of positrons in neutral and negative vacancies. Certain parameters used in the evaluation of f_{ps}, e.g., the bulk annihilation rate (λ_{s}), the positron diffusion length (L_{+}), the diffusion coefficient (D_{+}) and the implantation profile parameter (A), have been taken from the experiments. The calculated values of f_{ps} as a function of incident positron energy and temperature in Ge(110) and Si(111) have been compared with the experimental results. It has been found that in general the calculated results are in good agreement with the experimental ones. The calculation also confirms that the trapping rate of positrons into negative vacancy has a T^{-1/2} dependence with respect to the temperature.

Keywords

EN

78.70.Bj; 71.60.+z; 68.35.Fx

Discipline

• 71.60.+z: Positron states(for positron annihilation, see 78.70.Bj)
• 78.70.Bj: Positron annihilation(for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
• 68.35.Fx: Diffusion; interface formation(see also 66.30.-h Diffusion in solids, for diffusion of adsorbates, see 68.43.Jk)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 1999
• Volume: 95
• Issue: 6
• Pages: 1005-1012

Dates

published

1999-06

received

1998-05-04

(unknown)

1998-12-08

(unknown)

1999-03-30

Contributors

author

S. Shrivastava

• School of Studies in Physics, Vikram University, Ujjain (M.P.), 456010 India

author

A. Upadhyay

• School of Studies in Physics, Vikram University, Ujjain (M.P.), 456010 India

Identifiers

DOI

10.12693/APhysPolA.95.1005