Subbandgap photoluminescence and electroluminescence at n-GaN electrodes in aqueous solutions

• Published in: Journal of the Electrochemical Society Vol. 150; no. 10; pp. G602 - G606
• Main Authors: HUYGENS, I. M, GOMES, W. P, THEUWIS, A, STRUBBE, K
• Format: Journal Article
• Language: English
• Published: Pennington, NJ Electrochemical Society 01.10.2003
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electroluminescence; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Other luminescence and radiative recombination; Physics; Inorganic compounds; Aqueous solutions; Gallium nitrides; Photoluminescence; n type semiconductor; Electroluminescence; Experimental study; III-V semiconductors
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1603251

Photoluminescence (PL) and electroluminescence (EL) measurements were performed on n-GaN layers in contact with aqueous solutions. In both cases, strong subbandgap emission was observed. The PL spectra consisted of the well-known yellow emission band at 2.2 eV. The potential dependence of the intensity of this band was analyzed according to the Gartner model, showing that PL originates from the bulk of the semiconductor. Deviations from the simple Gartner model were found, indicating a finite rate of hole consumption at the electrode surface. The EL spectra, recorded at etched electrodes in persulfate solutions, were blue-shifted with increasing cathodic current density. It was shown that this shift is correlated to the presence of an extra luminescence band, appearing in the EL spectra at low current densities, which may be ascribed to radiative recombination via (near)surface states.