The interaction of thin gold layers deposited onto GaP substrate has been investigated. The volatile component loss of Au/GaP samples, heat treated in a vacuum and quenched from characteristic temperatures, was monitored in situ by the evolved gas analysis (EGA) and then the surfaces of these samples were analysed ex situ by secondary-ion mass spectrometry (SIMS) and scanning electron microscopy (SEM). The results obtained show that the interfacial reactions already take place at temperatures as low as 100 degrees C and become more intense as the temperature increases. As a consequence, the GaP in contact with Au starts to decompose at about 460 degrees C (under a vacuum pressure of 2-4*10-7 Torr) and a new phase (probably an AuGa intermetallic compound) forms. A giant evaporation peak of phosphorus is then observed at the characteristic temperature of about 500 degrees C. SIMS analysis confirms that on the surface of Au/GaP samples, quenched from this temperature, a high amount of phosphorus still remains. Above the characteristic temperature, the rising ratio of AuGa2+/AuGa+ clusters and the morphological changes of sample surface seem to indicate the formation of another inter-metallic compound (probably AuGa2) at a temperature of about 600 degrees C. These results are in good agreement with the theoretical considerations of Pugh and Williams (1986).
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry