Photoluminescence quenching and negative diamagnetic shift in GaP-InP lateral nanowires

The general behavior of the exciton diamagnetic shift is quadratic in low magnetic fields (ΔEdia∼B2) and linear in high magnetic fields (ΔEl∼B). A negative energy shift is difficult to imagine when using the features of... [ view full abstract ]

The general behavior of the exciton diamagnetic shift is quadratic in low magnetic fields (ΔEdia∼B2) and linear in high magnetic fields (ΔEl∼B). A negative energy shift is difficult to imagine when using the features of the normal diamagnetic shift. In this work, we report the magneto-exciton transitions of an InP/GaP lateral nanowire structure that was grown using a lateral composition modulation (LCM) growth technique. Linearly polarized photoluminescence (PL) measurements were made under pulsed magnetic fields to 50 T. We observed the normal diamagnetic shift from the direct InP nanowire transition and PL intensity quenching below 60 K at B=0T. However, the indirect InP-GaP transition exhibits no energy shift or negative energy shift depending on the magnetic field directions.
Fig. (1) depicts a schematic of the sample structure wherein three layers of lateral nanowires are aligned along the [1-10] direction. Fig. (2) shows the band alignments of the lateral nanowires (direct and indirect) and their PL transitions in different magnetic and polarization directions. Figure (c) alignment (indirect transition) shows strong negative diamagnetic shift. The direct transition exhibits PL intensity quenching behavior below 60 K. We will discuss negative diamagnetic shift and PL quenching by exciton center of motion and mobility enhancement, respectively