Structural comparison of gadolinium and lanthanum silicate films on Si(1 0 0) by HRTEM, EELS and SAED

High-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and selected area electron diffraction (SAED) were used to study gadolinium and lanthanum silicate films deposited on Si(100) substrates using electron-beam evaporation from pressed-powder targets. As-deposited films consist of an amorphous silicate layer without an interfacial layer. After annealing at 900°C in oxygen for 2min, an interfacial SiO2 layer is formed in the gadolinium silicate film, while this interfacial layer is a SiO2-rich lanthanum silicate layer in the lanthanum silicate film. The formation of interfacial silicate layers is thermodynamically more favorable for the lanthanum films than for the gadolinium films. The gadolinium silicate films crystallize at a temperature between 1000 and 1050°C, while the crystallization temperature for the lanthanum silicate films is between 900 and 950°C.