The influence of indium doping on the [1̄10] indentation cracks in (100) n-type gallium arsenide

Abstract

Microhardness indentation was used to determine the hardness and the microcrack anisotropy in In-doped gallium arsenide as a function of the doping level, indentation load and temperature. The hardness decreased with temperature from 600 kg/mm2 at room temperature to 50 kg/mm2 at 400 °C. There was no apparent influence of indium doping on the microhardness up to the maximum doping level, 0.41 at. %. However, the [110] and [1̄10] radial cracks emanating from the intersection of the Vickers diamond indentation diagonals varied significantly with temperature (in the range of room temperature to 250 °C) and doping level (up to a maximum of 0.41 at. %). Both crack orientations exhibited a maximum of the crack length at approximately 150 °C. The maximum in the crack length decreased and the spread of the crack lengths with temperature broadened out as the doping increased; the longest crack was 80×10−6 m for the undoped sample and 60×10−6 m for the sample doped to 0.41 at. %.The radial crack lengths varied with load as K=PCn, where n=0.65 at all temperatures except 200 °C, in which case n=0.77. This larger value of n has been associated with a transition in deformation mode at 1N. Scanning electron microscopy of the indentations showed that the [1̄10] cracks were discontinuous, suggesting that healing of these cracks may have occurred.