Luminescent Properties of Electrochemically Etched Gallium Arsenide

Abstract

The paper presents the results of structural and photoluminescent (PL) studies of porous GaAs layers created by electrochemical etching of GaAs wafers. Structural and morphological properties of porous GaAs were analyzed by SEM and Auger spectroscopy. The analysis of SEM images shows the presence of meso-and macropores and nanocrystallites in the porous layer. Some samples have the pyramidal formations on the surface. Auger spectra of crystalline and porous GaAs show different stoichiometry of the samples. The photoluminescence of the formed material is characterized by the emission band in the region of 1.5-3.2 eV, and the dependence of the PL spectrum on the wavelength of exciting light is observed. As the wavelength of the exciting light increases, the maxima of the emission spectra shift to the region of lower energies. This behavior of the PL spectrum (shift of the PL maximum depending on the wavelength of excitation emission) is characteristic of heterogeneous in thickness electrochemically etched porous structures. The nature of the multiband PL spectrum of porous GaAs can be explained by the existence of hydrated oxides of arsenic and gallium on the surface of the samples and the formation of nanocrystallites in the porous layers of GaAs. The article presents an estimation of the possible sizes of nanocrystallites under the assumption that PL is created due to quantum-dimensional effects.