DSL Photoetching: Principles and Application to Study Nature of Defects in III-V Materials

Abstract

After a short general description of the chemical etching of semiconductors the mechanisms of defect-selective etching are described in detail. Two distinct mechanisms that 1ead to the formation of etch pits and etch hillocks on dislocations emerging at a semiconductor surface are discussed. The principles of the formation of defect-related etch features are described for the HF-CrO3-H2O etching system used for etching of GaAs. A model of surface reactions is presented and the influence of illumination during etching on the defect-selectivity is emphasized. The use of ultra sensitive photoetching to study the nature and origin of complex defects in SI and n-like GaAs is documented. In particular, the concept for the formation of dislocation cell structure in undoped GaAs is presented and the ability of photoetching to reveal the structural changes during annealing is visualized.