Insulating layers of polycrystalline GaAsS compounds grown by reactive plasma sputtering

GaAsS ternary compounds are obtained from reactive radio-frequency cathodic sputtering of a monocrystalline gallium arsenide target in an argon and su lfurous hydrogen plasma. Thin films deposited on temperature controlled mol ybdenum substrates enable us to obtain a sandwich structure. Au/GaAsS/Mo. E lectrical (current-voltage) characterizations show a change, with sulfur co ncentration, in the compound behavior, from a highly doped semiconductor to a heavily insulating material. Maximum serial resistivity (3 x 10(14) Omeg a cm) is attained with a sulfur concentration of 50% (arsenic concentration being nearly 0%) and a typical space-charge-limited (SCL) conduction is ob tained. We determine dielectric permitivity from capacitative measurements. This material presents insulating properties (varying with sulfur concentr ation equivalent to those of SiO2 compounds. Moreover epitaxial layers can be grown on GaAs substrate, which will lead to applications in GaAs technol ogies as an insulator or an interface (depending on lattice parameter). (C) 1999 Elsevier Science S.A. All rights reserved.