Optical near-field photocurrent spectroscopy: a tool for nondestructive analysis of optoelectronic devices

Summary form only given. Here, we describe and demonstrate the potential of optical near-field photocurrent spectroscopy (NPCS) for analyzing microscopic aging processes in optoelectronic devices. The technique combines the subwavelength spatial resolution of near-field optics with tunable laser excitation, allowing for selective excitation of specific parts of the device structure, e.g., of low-energy impurity states, the active region, or the surrounding waveguide structures. We present experiments on GaAs-AlGaAs high-power laser-diode structures at a variety of excitation wavelengths before and after accelerated aging procedures.