Control of coherent acoustic phonon generation with external bias in InGaN/GaN multiple quantum wells

Control of acoustic phonon generation with external bias is demonstrated for an InGaN light-emitting diode by performing femtosecond pump–probe measurements. The evolution of both the carrier dynamics and the acoustic phonon strength with an external bias reveals that the acoustic wave is generated during the carrier sweeping process of the depletion field, where electric field screening accompanies stress of the lattice for a piezoelectric material.