HREM at orthogonal projections of GaAs islands on silicon

High Resolution Electron Microscope (HREM) studies typically examine only one projection of a structure and information in the electron beam direction is lost. In most cases, the structure in this direction is uniform and already known, but in others a second projection needs to be observed. This could involve preparing a second specimen sectioned at right angles to the first, or as described here, tilting a specimen through plus or minus 45 degrees and observing the same volume in orthogonal projections. The specimen used here was of GaAs islands on silicon, examined in the Atomic Resolution Microscope.