EBIC microscopy of double-heterostructure laser materials and devices

The electron beam induced current (EBIC) mode of the scanning electron microscope (SEM) has been used to characterize double heterostructure laser materials and devices in GaAs/Ga_1–xAl_xAs. Scanning the electron probe across the cleaved face of the laser structure shows that displacement of the p-n junction with respect to the heterojunctions is not uncommon with displacements ～ 1 μm occurring. Concurrent measurement of the minority carrier diffusion length gives very short lengths of 0·3–0·4 μm, differing from those in much thicker layers. Scanning the electron probe in the contact plane indicates clearly that long-lived lasers exhibit marked heterogeneity during degradation. Considerable complexity and variation is recorded depending upon the fabrication details and degradation conditions adopted.