Automation of Channeling Experiment for Lattice Strain Measurements Using High Energy Ion Beams

Abstract

40 MeV Si channeling studies have been performed on the strained In0.1Ga0.9As layer grown on GaAs substrate using Molecular Beam Epitaxy (MBE). Three samples with different layer thickness have been investigated in this study. Channeling experiment has been fully automated so as to minimize the radiation damage. Suitable software and hardware have been developed to control the precision goniometer using the CAMAC (Computer automation and control) based data acquisition system. In low energy He channeling, strain measurements are often misled by the beam steering effects caused due to broad critical angles if the strain is very low. Such effects can be minimized by increasing the probing beam energy as the channeling critical angle is inversely proportional to the square root of the incident energy. Hence small angular misalignments can also be resolved in the high energy channeling experiments. Heavy ions are chosen so as to have reasonably high scattering cross-section and also to avoid the nuclear reactions.