Pressure-Induced Resonance Raman Scattering in Ga sub (1-x) In sub x As/Ga sub (1-y) Al sub y As Strained Quantum Well Structures.

Pressure-tuned Resonance Raman Scattering (RRS) experiments in Ga sub (1-x) In sub x As/Ga Ga sub (1-y) Al sub y strained layer quantum-well samples with x = 0.15 and y = 0.15, on GaAs substrate, are reported. The photoluminescence (PL), the 2 LO and the LO-phonon Raman scattered intensities were followed as a function of pressure using the diamond cell. In back scattering geometry and with (100) samples, three sharply defined 2 LO- phonon resonances are observed 2.1, 3.8 and 5.2 GPa, with 647. 1 nm excitation (h bar for omega sub L =1.916 eV) and these are identified to be from the AlGaAs, GaAs and InGaAs layers respectively. At the above pressures, the 2 LO peak of the layer falls right on top of the PL peak of the corresponding layer, revealing that the resonance occurs occurs when E sub O = h bar for omega sub s (2 LO).