Two-photon optical beam induced current imaging of indium gallium nitride blue LEDs

In this study, InGaN light emitting diodes (LEDs) are characterized by optical beam induced current (OBIC) and photoluminescence laser scanning microscopy through two-photon excitation. Light scattering and absorption in the packaging material and the p-doped top layer of the LEDs are greatly reduced as a result of employing longer excitation wavelength with energy less than the band gap of the top p-layer. When compared with single photon OBIC, two-photon OBIC imaging not only exhibits superior image quality but also reveals more clearly the characteristics of the epilayers focused on.