Epilayers of packaged indium gallium nitride light-emitting diodes (LED’s) 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 LED’s are greatly reduced as a result of employing a longer excitation wavelength, with energy that is less than the bandgap of the top p layer. 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 that are being focused on.
© 1999 Optical Society of America
Fu-Jen Kao, Mao-Kuo Huang, Yung-Shun Wang, Sheng-Lung Huang, Ming-Kwei Lee, and Chi-Kuang Sun, "Two-photon optical-beam-induced current imaging of indium gallium nitride blue light-emitting diodes," Opt. Lett. 24, 1407-1409 (1999)