INCORPORATION PROCESS OF THE AS ATOM ON THE INP(001) SURFACE STUDIED BY EXTENDED X-RAY-ABSORPTION FINE-STRUCTURE

The incorporation process of As atoms during metalorganic vapor phase epitaxy (MOVPE) has been studied by extended X-ray absorption fine structure (EXAFS). The growth of InP(001) was interrupted and the surface was exposed to arsine (AsH3) for the investigation of the incorporation of As atoms during the AsH3 gas flow interval. It was found that the As atoms replace the P atoms, from the analysis of the As K-edge EXAFS. The amount of the incorporated As atoms as a function of the AsH3 exposure time shows that the substitution consists of two processes with different time scales. In the fast process, which saturates in a few seconds, the incorporated As atoms substitute the P atoms on the surface with an anomalous bond length relaxation, while the slow process continues in the subsurface over a wide rage of the exposure time.