Structural change of atomic-order nitride formed on Si_{1 - x}Ge_x(100) and Ge(100) by heat treatment

Thermal stability of atomic-order nitrided Si(100), Si_0.6Ge_0.4(100) and Ge(100) formed in NH₃ gas environment at 400 °C and structural change of the nitrided surface were investigated. It was found that N atom amount on Ge(100) tends to decrease at higher heat-treatment temperatures above 400 °C. Especially with H₂ heat treatment, the N atom amount on Ge(100) becomes below detection limit for X-ray photoelectron spectroscopy measurement. On the other hand, it was confirmed that the N atom amount on Si(100) and Si_0.6Ge_0.4(100) is almost independent of heat-treatment conditions in the temperature range of 400-700 °C. From the change of chemically shifted components in Si 2p and Ge 3d spectra for Si_0.6Ge_0.4(100), it is suggested that N atoms bound to Ge atoms tend to be transferred to Si atoms at higher heat-treatment temperatures above 400 °C.