Raman scattering of Ge/Si dot superlattices under hydrostatic pressure
We have studied the self-organized Ge/Si quantum dots (QD's) by Raman scattering under hydrostatic pressure near resonance and off resonance with confined Ge-like E{sub 1} transition. The Raman spectra of Ge-Ge, Si-Ge, and the Si acoustic phonon (Si-2TA) modes were obtained as function of pressures in the range 1--70 kbar. Our results show that the Ge-Ge and Si-2TA modes can be easily resolved at low pressure due to a high degree of compressive built-in strain in the Ge layers. The mode Grueneisen parameter of the Ge-Ge phonon mode in QD's is found to be {gamma}=0.81{+-}0.01, which is smaller than the corresponding quantity in bulk Ge. Normalized Raman intensity profiles of Ge-Ge mode exhibit a resonance enhancement peak at {approx}32 kbar. The pressure coefficient {alpha} of this resonating electronic transition thus obtained is {approx}5{+-}1meV/kbar. This value is smaller than the pressure shift of the E{sub 1} transition in bulk Ge.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40230862
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 7 Vol. 64; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
Similar Records
Hydrostatic pressure studies of the Raman-active phonon modes in the bulk high-temperature superconductor YBa[sub 2]Cu[sub 4]O[sub 8]
Raman and photo-modulated reflectivity studies of ZnTe/InAs semiconductor heterostructure under hydrostatic pressure