Segregations and desorptions of Ge atoms in nanocomposite Si1-xGex films during high-temperature annealing

摘要

Nanocomposite Sil-xGex 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 (Ta) is 900 ℃,the nanocomposite Si1-xGex 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.