Etching Studies of Anomalous Defects in P‐Type GaP Crystals

Abstract

Anomalous defects in crystals prepared by Czochralski, solution‐growth, and vapor‐growth techniques have been investigated by chemical etching, optical microscopy, and scanning electron microscopy. These defects were found in as‐grown highly Zn−, Cd−, or crystals with carrier concentrations ranging from . Thermal oxidation of vapor‐grown crystals doped with Zn, or Cd, produced the same defect in the surface layers (20μ depth) of the crystals. The anomalous defects were developed distinctly by chemical etching as characteristic deep etch pits both on and on cleavage surfaces. These pits were distinguished from ordinary dislocation etch pits both by their morphology and etching behavior. The density of the pits was between 102 and 106/cm2. From detailed observation, it has been proposed that the anomalous defects are special dislocations modified with some impurities. It seems that the relevant impurities are zinc (or cadmium) and/or oxygen.