Preparation of (InGa)As/GaAs multilayered materials for TEM by one side non-rotation ion beam thinning.

A technique is described for the preparation of thin specimens for transmission electron microscopy (TEM) of (InGa)As/GaAs multilayered materials. In this technique, a shielding method is used for selective-area perforation by ion beam thinning. Thin cross-sectional specimen slices are mechanically pre-thinned to about 30 microns and then thinned by ion sputtering from one side of the specimen at a time without rotation of the specimen stage. No direct ion sputtering occurs at the growth surface of the specimen so that a specimen with thin areas containing the desired near-surface structures can be obtained. The recipe for this technique is given in detail. A patterning method for increasing the size of the thin area for TEM investigation is also described. It is shown that a smooth surface can be obtained by sputtering without rotating the stage if obstacles that produce redeposits onto the sputtered surface are removed.