We present microscopically-resolved photocurrent spectroscopy as a
new powerful analytical tool for the simultaneous detection of
packaging-induced strain and defects in GaAs-based high-power laser diode
arrays (cm-bars).
Using the Fourier-transform (FT) technique we measure photocurrent (PC)
spectra with a high spatial resolution of better than 50 μm at the active layer of the device. By analyzing this data, spatially resolved distributions of
strain as well as of defects are obtained. So far, PC measurements at cm-bars
have only provided an overview of the distribution of strain and defects in the device on an emitter-by-emitter scale. The high spatial resolution now allows
examination of the distribution of strain and defects even within one single
emitter. This is essential for obtaining insights into device failure
mechanisms and also makes a substantial contribution for improving device
performance and reliability.