Fabrication of MnAs microstructures on GaAs(001) substrates and their electrical properties

摘要

We explore wet and dry etching processes of thin MnAs layers grown on GaAs(001) substrates for microstructuring. Most of the common wet chemical etch solutions for GaAs react with MnAs strongly and in a peculiar manner. Unidirectional cracks are generated when the MnAs layers arc thicker than 100 nm. We demonstrate that the crack generation can be avoided by choosing a suitable etch solution or etch temperature. We fabricate submicrometer-wide MnAs wires using Ar ion milling. The resistivity of the narrow channels is measured over a temperature range covering the phase transitions in MnAs between the alpha, beta, and gamma phases. The resistivity along the MnAs[0001] direction is found to be smaller than that along the MnAs[11 (2) over bar0] direction regardless of the phase. A nearly linear temperature variation of the phase fraction is deduced in the alpha-beta phase coexistence regime. The temperature coefficients of the resistivities are negative for the nonmagnetic phases. (c) 2006 Elsevier Inc. All rights reserved.