X-RAY STANDING WAVE ANALYSIS OF AL/GAAS/SI(111)

The Al/GaAs interface formed on Si(111) is investigated by means of the X-ray standing wave technique. Different fluorescence profiles of Ga and As K-alpha are observed from a Al/GaAs/Si(111) sample. Comparing the results of Al/GaAs/Si(111) with GaAs/Si(111), most of the Ga atoms are found to change their positions randomly by evaporating Al metal on the GaAs films even at room temperature. On the contrary, most of the As atoms continue to maintain original positions in the diamond structure. This can be explained by interchanging the sites of Ga and Al atoms, and forming (Al, Ga)As layers. The results suggest that interdiffusion and interchange between Al and GaAs layers should not be neglected even at room temperature.