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A Process to Reveal Dislocations in Gallium Arsenide

IP.com Disclosure Number: IPCOM000096137D
Original Publication Date: 1963-Jan-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 79K

Publishing Venue

IBM

Related People

Woodall, J: AUTHOR

Abstract

Dislocations in gallium arsenide crystals can be shown quickly and accurately. Basically, a flat surface of disturbed material is prepared. This disturbed layer is then removed by chemical polishing. Other chemical methods then reveal the dislocations in the bulk material. Detailed operations are as follows: 1. A flat is lapped on the (111) A face of a crystal of GaAs using a glass plate and 17. 5 microns of Al2O3 powder. 2. The crystal is then cleaned with H2O. 3. The sample is etched to remove the disturbed layer with 1:3:4, HF:HNO3:H2O until the surface of the sample becomes shiny, left-hand drawing. 4. The sample is rinsed again with H2O. 5. The sample is etched in 1:3:1, H2O:H2SO4:H2O (30%) for 30 to 45 seconds. 6. The sample is then etched immediately in 5:1, 5% NaOH: 1H2O2 for 1 to 2 minutes. 7.

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A Process to Reveal Dislocations in Gallium Arsenide

Dislocations in gallium arsenide crystals can be shown quickly and accurately. Basically, a flat surface of disturbed material is prepared. This disturbed layer is then removed by chemical polishing. Other chemical methods then reveal the dislocations in the bulk material. Detailed operations are as follows: 1. A flat is lapped on the (111) A face of a crystal of GaAs using a glass plate and 17. 5 microns of Al2O3 powder. 2. The crystal is then cleaned with H2O. 3. The sample is etched to remove the disturbed layer with 1:3:4, HF:HNO3:H2O until the surface of the sample becomes shiny, left-hand drawing.
4. The sample is rinsed again with H2O. 5. The sample is etched in 1:3:1, H2O:H2SO4:H2O (30%) for 30 to 45 seconds. 6. The sample is then etched immediately in 5:1, 5% NaOH: 1H2O2 for 1 to 2 minutes. 7. The sample is rinsed in H2O and dried, right-hand drawing.

Other methods are to use steps 1, 6, 7 (a) or to mechanically polish and then use steps 5, 6, 7 (b). Method (a) does not completely remove the disturbed layer of the crystal before the actual process to reveal the dislocations is started. Hence, there is an inaccurate representation of the dislocations in the bulk material due to imperfections which may exist in the disturbed layer.

Method (b) is time-consuming and may also lead to an inaccurate representation. This method shows inaccuracies in the representation due to method (a).

This method, however, i...