Defect-selective etching of scandium nitride crystals

Defect-selective etching was developed for scandium nitride (ScN) crystals. ScN crystals were etched in fused KOH/NaOH eutectic mixtures between 180 and 440 °C for up to 10 min. Several etch pit shapes were observed, and their formation was dependent on the etching temperature. The different etch pit shapes probably originated from different crystalline orientations and defect types. Square etch pits with steps formed at screw and mixed dislocations, as verified by transmission electron microscopy. The density of the etch pits was on the order of 104–106 cm−2 for bulk ScN crystals produced by sublimation.