Investigating the lateral carrier diffusion in MBE grown InGaN quantum wells as function of quantum well width

A micro-photoluminescence setup is used to investigate the ambipolar diffusion of charge carriers in InGaN quantum wells (QW) grown by molecular beam epitaxy. The thickness of the active region varies between 2.6 and 25 nm. Our results show for all samples diffusion in the range of a few μm. Additionally, a larger QW thickness is accompanied by a smaller luminescence spot radius in our experiment. However, a larger dark carrier diffusion with increasing QW thickness cannot be excluded due to an increasing carrier lifetime. Moving away from the excitation center leads to a stronger tilt of the QW potential due to lower carrier density, consequently suppressing radiative recombination.