ANALYTICAL COLOR FLUORESCENCE ELECTRON-MICROSCOPY OBSERVATION OF LASER-DIODES

Laser diodes with the multilayer heterostructure have been observed in cathodoluminescence (CL) images using an analytical color fluorescenc e electron microscope. An AlGaInP/GaInP chip, which is commercially av ailable as 670nm red laser diode, emits red CL from a part of the p-Al GaInP layer just above the p-GaInP layer and between the n-GaAs blocki ng layers. A chip that has no blocking layers emits only very weak red CL, which indicates the strong relation of CL with laser emission. In images of a CdZnSe/ZnSe diode that emits 5 30 nm blue laser light at room temperature, a blue CL emission appears which is much stronger in the n-type region, in particular in the n-ZnSSe cladding layer, than in the p-type region. Fade-out of the blue CL and/or appearance of yel low-red emission take place in the area including dislocations.