Effect of Secondary Electroluminescence on Cathodoluminescence and Other Luminescence Measurements

Cathodoluminescence and photoluminescence measurements are commonly accepted as revealing local properties of a specimen region excited by a beam of electrons or photons. However, in the presence of a strong electric field (e.g. a junction) an electron (or light/laser) beam-induced current is generated, which spreads over the structure. A secondary non-local electroluminescence, generated by this current and detected together with the expected luminescence signal, may strongly distort measurement results. This was confirmed by cathodoluminescence measurements on test structures prepared by focused ion beam on AlGaAs/GaAs/InGaAs laser heterostructures. Methods for minimizing the distortion of measured luminescence signals are presented.