Defect related photoluminescence emission from etched GaAs microstructure introduced by electrochemical deposition

Gallium arsenide (GaAs) microstructures have been prepared by electrochemical anodic etching of GaAs substrate in an aqueous solution of H₃PO₄ (85 wt %): H₂O₂ (30 wt %): H₂O = 1: 2.5: 8. (NH₄)₂S solution was chosen to passivate the surface of GaAs micrcostructures. The surface morphology of microstructures were characterized by Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM). Photoluminescence (PL) mapping was also applied to characterize the defect related photoluminescence emission from GaAs microstructures. Compared to the GaAs microstructures which was treated by (NH₄)₂S solution, we can find that there was a defect peak located at 900 nm in the PL spectra of GaAs microstructures untreated. However, it disappears in the PL spectra of (NH₄)₂S-treated GaAs microstructures sample.