QUANTITATIVE STUDIES OF BEAM-INDUCED DEFECTS IN III-V COMPOUNDS BY CATHODOLUMINESCENCE AND TRANSMISSION ELECTRON-MICROSCOPY

Electron beam currents above about 1 muA induce long straight dislocations lying just below the surface in (001) wafers of GaAs and InP. These dislocations are of interest in themselves and are well situated for cathodoluminescence (CL) dark contrast studies. Microcomputer Monte Carlo electron trajectory simulation-based programs were written to calculate emitted CL intensities and to simulate defect CL contrast profiles. Series of simulations for increasing beam energies (penetration range) show that the dislocation contrast is a maximum for a certain accelerating voltage which enables the dislocation depth to be determined. The magnitude of the contrast for a given beam energy increases with increasing defect recombination strength which can therefore be identified. The possibility of finding the number of dislocations in individual dark line bundles is discussed. The results of further transmission electron microscopy observations on the beam-induced dislocations are also presented.