CS214254B1 - Method of etching for determination of crystalline grains of gallium arsenide crystalls - Google Patents

Description

CZECHOSLOVAKIASOCIALISTREPUBLIC <1S)

COPYRIGHT CERTIFICATE DESCRIPTION 214 254 (Π) (Bl)

(61) (23) Exhibition priority (22) Registered n 09 80 (21) PV 6145-80 (51) IntCl.5 H 01 L 21/302

OFFICE OFFICE

& DISCOVERY (40) Published 15 09 81 (45) Published 01 Q6 84 (75)

Author of the invention Rough Arnošt ing. Esc., Štěpánek Bedřich ing. Esc., Prague (54) Etching method for determination of crystalline grains of galliumarsenide crystals

BACKGROUND OF THE INVENTION The present invention relates to a process for etching crystals of gallium-arsenide for the determination of crystalline grains, wherein the crystals have been pre-treated by grinding or lapping, and a surface etched to gloss. and

The etching of the crystals for the determination of crystalline grains makes it possible to determine in a simple way whether the cultivated gallium crystal is a single crystal or composed of several grains.

There are a number of useful etchants and etching processes, but the solutions used so far have a number of disadvantages.

The use of Η ,, 02 + HF + HgO (RK Willardson, HL Goering: Preparation of III-VCompounds, vol. I. New Yourk, Reinhold Publ. Cer. (1962) is too time consuming. Etching takes 45 minutes. uses bromine, which is poisonous (L. Koszi, 'DL Rode: J. Olch.

Soc. 122/1975/1696 or by J.G. Grahmaier, C. B. Watson: Phys. St. Solidi 32/1969 / K 13) use strongly aggressive substances such as molten potassium hydroxide. The use of poisonous and highly aggressive substances makes work very difficult, as it is necessary to use complex safety measures, which are often detrimental to the accuracy of the result.

The use of the above-mentioned etchants is too time-consuming, both for the etching process itself and for ensuring all the necessary safety precautions (such as the described adhesives and processes appear uneconomical.

These disadvantages are eliminated by the etching method for the determination of crystalline gallium grains 214254

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Claims (2)

214254. 2 according to the invention, the essence of which is that the crystal of galliumarsenide is treated for 30 to 60 seconds at a temperature of 40 to. 60 ° C with an etchant containing 20 parts of a 40% aqueous solution of tartaric acid, 5 parts of concentrated nitric acid and 4 parts of an aqueous solution of silver nitrate, moving slightly in the solution. The advantage of this etching method is that it does not contain toxic and strongly aggressive substances, and the etching times are very short, so the process takes about 2 to 3 minutes. The materials used are cheap and readily available. Before etching for the determination of crystalline grains, the gallium-arsenide crystal is wet-milled with a fine carborundum powder and etched. to shine. After thoroughly washing the shiny surface and rinsing it in water, it is placed in a pre-prepared crystalline grain healing composition of the present invention. Etching is carried out in solution at a temperature of 40 to 60 ° C. The sample was gently moved through the etch for 30 to 60 seconds, then the substrate was thoroughly rinsed under flowing water and finally in distilled water. On a metallographic microscope at a magnification of 200-500x, the number of galliumarsenide specimens could then be observed. The following examples are intended to illustrate the invention without limiting it in any way. EXAMPLE 1 A perfectly polished crystal of galliumarsenide, etched to gloss, was thoroughly rinsed in an etchant to determine the knystalic grains of the composition of the invention. The etchant was at a temperature of 45 ° C and the galliumarsenide sample was left there for a mild stirring for 55 seconds. It was then removed and rinsed in flowing water and extracted in distilled water. Drying was observed on a metallographic microscope. It consisted of several well-visible grains. EXAMPLE 2 A well-polished crystal of galliumarsenide, etched to a gloss, was thoroughly rinsed in an etchant to determine the crystalline grains of the composition of the invention. The etchant had a temperature of 57 ° C and the gallium sarcoside sample was left there with mild agitation for 40 seconds. Then it was removed, thoroughly rinsed in flowing water and finally in distilled water. After drying, it was observed on a metallographic microscope. The galliumarsenide sample was folded from several well-developed grains. The method of etching for the determination of crystalline grains of the invention can be used in all laboratories where crystalline gallium arsenide is prepared. The etching of the crystals for the determination of the crystalline grains makes it possible to determine in a simple way that the newly grown crystal is a single crystal, or is composed of several grains. characterized in that a composition of 20 parts of an aqueous solution of tartaric acid at a concentration of 40%, 5 parts concentrated and 4 parts of an aqueous solution of silver nitrate 1% for a temperature of 40-60 ° C is applied to the gallium-arsenide salt;