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Identification of Charge States of Indium Vacancies in InP

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LiMing W., Fung S., Beling C.

Acta Physica Polonica A

1999

vol. 95

issue 4

612-614

The autocorrelation functions of positron-electron pairs in InP with indium vacancies in different charge states are calculated in this work. It is found that the autocorrelation function can be used to identify the charge states of vacancies in solids. In the case of perfect lattice the autocorrelation function oscillates on the lattice with the periodicity of the lattice and decays gradually up to about the third layer of the lattice points. In the case of neutral vacancies, the central peak expands significantly, but the nearest peak and dip are greatly reduced. In the case of negative charge states of vacancies, the central peak, however, contracts slightly compared to the case of the perfect lattice, and the nearest peak and dip and the next-nearest peak nearly disappear.

A Real-Time S-Parameter Imaging System

100%

Naik P., Cheung C., Beling C., Fung S.

Acta Physica Polonica A

2005

vol. 107

issue 5

761-768

Obtaining a lateral S-parameter image scan from positrons implanted into semiconductor devices can be a helpful research tool both for localizing device structures and in diagnozing defect patterns that could help interpret function. S-parameter images can be obtained by electromagnetically rastering a variable energy positron beam of small spot size across the sample. Here we describe a general hardware and software architecture of relatively low cost that has recently been developed in our laboratory which allows the whole sub-surface S-parameter image of a sample or device to be obtained in real time. This system has the advantage over more conventional sequential scanning techniques of allowing the operator to terminate data collection once the quality of the image is deemed sufficient. As an example of the usefulness of this type of imaging architecture, S-parameter images of a representative sample are presented at two different positron implantation energies.

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2 Acta Physica Polonica A

1 2005

1 1999

2 Beling C.

2 Fung S.

1 Cheung C.

1 LiMing W.

1 Naik P.

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Identification of Charge States of Indium Vacancies in InP

A Real-Time S-Parameter Imaging System