Fig. 5

Steady-state PL characterization of MPB SCBK at different regions.a–d Around cathode, e–h in center region, and i–l around anode with different applied bias and removing bias. The variation in the a, e, and f waterfall map of the steady-state PL spectra and b, f, j PL maximum intensity with different applied biases. The variation in the c, g, and k waterfall map of the steady-state PL spectra and d, h, l PL maximum intensity after removing bias. m Fluorescence confocal micrograph of the area between the electrodes and the center region with different applied biases and upon removing the bias