Ga migration process in Au film on (100) GaAs under temperature treatment in vacuum

The investigated structures look like patterns with separated circular windows, opened in SiO2 covering GaAs surface with thin metal film (Au) deposited above (honey-comb structures). The method of precise chemical analysis developed and used in this work allowed to determine the total quantity of Ga in Au layer rubbed off the substrate. It was found that at the initial stage of heating (up to 400°C) Ga migration from windows (Au on GaAs) into Au on SiO2 had not been observed but physical and chemical reactions with forming of Au-Ga eutectic compound were found in Au layer on GaAs. The melting temperatures and specific melting heat were calculated from experimental data (T0 = 340°C;Q0 = 3.5kcal/mol). After temperature increasing Ga migration in Au on SiO2 was noticed and identified as a result of diffusion process with Au-GaAs windows as ‘sources’ and Au on SiO2 as ‘drains’. The process of Ga migration manifests itself for 500A˚Au and 0.2–0.3 μm SiO2 thickness as the grain boundary diffusion with activation energy ∼ 7.3 kcal/mol.