Ultrafast dephasing of coherent optical phonons in atomically controlled GeTe/Sb2Te3 superlattices

作者：Hase Muneaki^*; Miyamoto Yoshinobu; Tominaga Junji

来源：Physical Review B, 2009, 79(17): 174112.

DOI：10.1103/PhysRevB.79.174112

• amorphous semiconductors
• annealing
• antimony compounds
• germanium compounds
• high-speed optical techniques
• phonon-defect interactions
• semiconductor superlattices

Femtosecond dynamics of coherent optical phonons in GeTe/Sb2Te3 superlattices (SLs), a new class of semiconductor SLs with three different states, have been investigated by using a reflection-type pump-probe technique at various lattice temperatures. The time-resolved transient reflectivity obtained in as-grown SLs exhibits the coherent A(1) optical modes at 5.10 and 3.78 THz while only the single A(1) mode at 3.68 THz is observed in annealed SLs. The decay rate of the A(1) mode in annealed SLs is strongly temperature dependent while that in as-grown SLs is not temperature dependent. This result indicates that the damping of the coherent A(1) phonons in amorphous SLs is governed by the phonon-defect (vacancy) scattering rather than the anharmonic phonon-phonon coupling.

• 出版日期2009-5