Atomic-Scale Investigation of Hydrogen Platelet Defects in Proton-Bombarded n-Type GaAs using Probe-Cs-Corrected STEM and 4D-STEM

Abstract

Probe-Cs-corrected high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) and 4D-STEM ptychography were used to investigate planar defects on {111} planes in high-dose proton-bombarded n-type GaAs. The defects, present at the projected range of implanted 300 keV protons to a total dose of 1017 H+ cm-2, consist of single or double self-interstitial GaAs {111} dislocation loops, but also a newly observed platelet-like planar {111} disruption without a self-interstitial layer. These lower-density zones are proposed to be hydrogen platelet structures, consisting of molecular H2 agglomerations trapped at tetrahedral interstitial sites. This work explores the use of experimental 4D-STEM phase retrieval techniques to visualise possible H2 configurations in this new defect