ASTM F 418 : 1977 : R2002

1.1 This practice covers a procedure to be followed to free the constant composition region of epitaxially grown gallium arsenide phosphide, GaAs_(1x)P_x, from the substrate and graded region on which it was grown in order to measure the electrical properties of only the constant composition region, which is typically 30 to 100 m thick. It also sets forth two alternative procedures to be followed to make electrical contact to the specimen.

1.2 It is intended that this practice be used in conjunction with Test Methods F 76.

1.3 The specific parameters set forth in this recommended practice are appropriate for GaAs_{0. 62}P_{0. 38}, but they can be applied, with changes in etch times, to material with other compositions.

1.4 This practice does not deal with making or interpreting the Hall measurement on a specimen prepared as described herein, other than to point out the existence and possible effects due to the distribution of the free carriers among the two conduction band minima.

1.5 This practice can also be followed in the preparation of specimens of the constant composition region for light absorption measurements or for mass or emission spectrometric analysis.

1.6 This practice becomes increasingly difficult to apply as specimens become thinner.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For hazard statement, see Section 9 and 11.9.2.4.