Optical near-field photocurrent spectroscopy: A new technique for analyzing microscopic aging processes in optoelectronic devices

The potential of optical near-field photocurrent spectroscopy for analyzing microscopic aging processes in optoelectronic devices is demonstrated, The technique combines the subwavelength spatial resolution of near-field optics with tunable laser excitation, allowing for selective investigation of specific parts of the device structure, Experiments on GaAs/(AlGa)As high power laser diodes before and after accelerated aging provide direct visualization of defect growth within the p-i-n junction and information on aging-enhanced recombination processes close to the laser facet. The effect of wave guiding of the exciting light on the image formation is discussed. The nondestructiveness makes this technique a particularly attractive method for in situ analysis in high power laser diodes. (C) 1996 American Institute of Physics.