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Analysis of gallium arsenide by spark-source mass spectrometry (CAT#: STEM-ST-0291-LJX)

Introduction

A method has been developed for analysing gallium arsenide with a resistance of greater than 10(9)Omega by spark-source mass-spectrometry, without the need for pelleting, which introduces a prohibitively high level of contamination and lowers the detection limit for a given exposure. It uses a gold evaporation technique, whereby a thin layer of 99.999% pure gold is deposited on one surface of the GaAs electrodes, in a chamber mounted on the ion-source. No contamination, other than gold, is introduced into the sample at a level of 50 ng/g or greater. It is possible to detect carbon in the sample at the 1-2 mug/g level. The sample preparation time is less than 30 min, and more than one set of samples can be gold-coated at a time.




Principle

By using vacuum spark discharge, the energy accumulated in a small volume can make the material in the volume suddenly evaporate and ionize, so as to obtain the characteristic ion current information.

Applications

(1) Solid spark source mass spectrometry: impurity analysis of high-purity materials, which can be applied to semiconductor materials, non-ferrous metals, and building materials industries;
(2) Gas isotope mass spectrometry: determination of stable isotopes C, H, N, O, S and radioactive isotopes Rb, Sr, U, Pb, K, Ar, which can be applied to geology, petroleum, medicine, environmental protection and agriculture.

Procedure

(1) An electric field is applied between the electrodes to ionize part of the carrier gas (such as argon) in the electric field;
(2) The "cathode ray" or "anode ray" generated by ionization accelerates in the direction of the opposite polarity in the residual gas, bombards the anode or cathode, and vaporizes a part of the substance to be measured on the plate;
(3) Part of the atoms of the vaporized substance are ionized in the subsequent discharge process.

Materials

• Sample Type:
Gallium arsenide

Notes

Before starting the machine, check whether the water (water cooler), electricity, gas (argon/nitrogen), temperature, humidity, and exhaust air of the instrument are normal.
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