Investigation of Inhomogeneities in GaAs by Electron-Beam Excitation

Abstract

Striations concentric with the growth axis, which are usually considered as impurity fluctuations, represent the inhomogeneity most frequently encountered in . Images of such striations were obtained by scanning‐electron‐beam‐excited recombination radiation (SEBERR) and displayed on a cathode‐ray tube. The samples investigated were Te‐doped, floating‐zone containing free electrons‐cm−3. The spectral shape of recombination radiation demonstrated that any variation in free electron concentration within a cross section normal to the growth axis must be less than about 10%. In addition, the spectral shape showed that compensation is not the reason for the difference in the Te concentration and the free electron concentration. Precipitation of a Te‐rich ternary solid solution with a crystal structure other than may be the most consistent explanation for the striation inhomogeneity and also may account for the cathodoluminescent features associated with dislocations.