Segregations and desorptions of Ge atoms in nanocomposite Si_1-xGe_x films during high-temperature annealing

Nanocomposite Si_1-xGe_x films are deposited by dual-source jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD). The segregations and desorptions of Ge atoms, which dominate the structural evolutions of the films during high-temperature annealing, are investigated. When the annealing temperature (T_a) is 900℃, the nanocomposite Si_1-xGe_x films are well crystallized, and nanocrystals (NCs) with the core-shell structure form in the films. After being annealed at 1000℃ (above the melting point of bulk Ge), Ge atoms accumulate on the surfaces of Ge-rich films, whereas pits appear on films with lower Ge content, resulting from desorption. Meanwhile, voids are observed in the films. A cone-like structure involving the percolation of the homogeneous clusters and the crystallization of NCs enhances Ge segregation.