Raman study of InAs quantum dots on GaAs/InP grown by low pressure metal-organic chemical vapor deposition

Raman spectra of InAs quantum dots (QDs) on InP substrate were investigated. Both longitudinal-optic (LO) and transverse-optic (TO) frequency of InAs QDs showed a large blue-shift comparing to its bulk due to the compressive strain in InAs QDs. Raman scattering of InAs QDs with a thin GaAs interlayer was studied. We obtained that the peak position of LO and TO mode of InAs QDs became larger blue-shifted when we inserted the GaAs layer. At the same time, we found a red-shift of the frequency of GaAs LO mode because of tensile strain. Theoretical calculation was performed and its prediction coincided with our experiment results well. They both showed that strain played an important role in formation of InAs QDs.