Abstract :
Properties of metal contacts on III–V semiconductors are dependent on the electronegativity of the metal. Generally metals have been classified into three categories according to their behaviour upon heat treatment. Au, Ni and W are the three metals belonging to different categories with the descending order of electronegativity. In this study a low energy positron beam has been used to investigate as-grown View the MathML source (SI), View the MathML source (SI) and View the MathML source (SI) samples with different thicknesses of metal overlayers. The method that has been employed is that of monitoring the Doppler broadening of annihilation radiation through S parameter measurements as a function of the beam energy. The S-E data were analysed by the program VEPFIT with different models and different implantation profiles. It is found that the interfacial information able to be extracted from the fitting is limited by present uncertainties in the implantation profile.
