TEM Cross Section Sample Preparation Technique for III–V Compound Semiconductor Device Materials by Chemical Thinning

Abstract

A cross section sample preparation technique is described for the TEM studies of III–V compound semiconductor device materials. In this technique, a grid‐masking method is introduced for selective‐area perforation using chemical etching. By epoxy bonding a TEM specimen grid onto the surface of a face‐to‐face or face‐to‐back epoxy‐bonded thin cross section sample stack, perforations by chemical etching are confined to the regions inside the meshes. Selective‐area perforation can easily be achieved by accurately positioning the masking grid and monitoring the perforation under a microscope. Since many perforations can be made in the selected area, the chance of obtaining a cross section sample containing the device structure is greatly increased. Furthermore, the masking grid mechanically reinforces the perforated sample and hence eliminates problems associated with sample handling. Examples of the use of this technique for single‐layer and , multilayer laser device structures, grown by vapor‐phase epitaxy, are demonstrated. The technique is also applicable to multilayer structures, and, in addition, greatly facilitates the selective‐area perforation of plan‐view TEM samples.