The use of GaAs for semiconductor devices requires a consistent atomic lattice structure. However, lattice or crystal line defects of various types and quantities are always present, and rarely homogeneously distributed. It is important to determine the mean value and the spatial distribution of the etch pit density.

1. Scope

1.1 This test method is used to determine whether an ingot or wafer of gallium arsenide is monocrystalline and, if so, to measure the etch pit density and to judge the nature of crystal imperfections. To the extent possible, it follows the corresponding test method for silicon, Test Method F 47. Test Method F 47 also presents the definition of many crystallographic terms, applicable to this test method.

1.2 This procedure is suitable for gallium arsenide crystals with etch pit densities between 0 and 200 000/cm².

1.3 Gallium arsenide, either doped or undoped, and with various electrical properties, may be evaluated by this test method. The front surface normal direction of the sample must be parallel to the <001> within ± 5° and must be suitably prepared by polishing or etching, or both. Unremoved processing damage may lead to etch pits, obscuring the quality of the bulk crystal.

1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D1125 Test Methods for Electrical Conductivity and Resistivity of Water

E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

F26 Test Methods for Determining the Orientation of a Semiconductive Single Crystal

F47 Test Method for Crystallographic Perfection of Silicon by Preferential Etch Techniques3

Keywords

crystal perfection; etch pit density; gallium arsenide; potassium hydroxide etch; semiconductor; single crystal; Contamination semiconductors; Crystal lattice structure; Defects semiconductors; Density electronic applications; Etching (materials/process); Etch pit density (EPD); Gallium arsenide; Impurities electronic materials/applications; KOH etch pits; Microscopic examination electronic materials; Molten KOH etch technique; Monocrystalline perfection;

ICS Code

ICS Number Code 71.060.50 (Salts)

Citing ASTM Standards

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