Raman determination of carrier concentration in ZnO-based heterostructure light-emitting diodes.

Understanding of the carrier concentration properties of current spreading layers in LED devices is important although difficult to achieve. Here, we present a solution to determine the carrier concentration for current spreading layers in ZnO-based LEDs, based on Raman spectroscopy. Raman spectra and lineshape fitting indicate a hole concentration below 1×1018 cm-3 in the p-type region and an electron concentration of 1.21×1019 cm-3 in n-type. The results from Raman spectroscopy are further qualitatively confirmed by the electroluminescence spectrum and device simulation, which demonstrates its possible application in carrier concentration assessment in multilayered structures.