Effect of Solvent Polarity on Surface Characteristics and Luminescent Properties of Octadecanethiol Passivated GaAs

In order to effectively reduce the surface state density of GaAs and obtain a stable high-performance passivation film, the GaAs surface was passivated by using the solution of octadecanethiol in different solvents. The effects of solvent polarity on passivated GaAs surface by octadecyl mercaptan solution were researched by X-ray diffractometry, photoluminescence and atomic force microscopy. The XPS test shows that the methanol compared to ethanol and isopropanol solvents, the surface of the GaAs after passivation has less oxide content, the As-S bond increases, and the density of octadecanethiol molecules attached to the surface increases. The PL measurement shows that the PL intensity of GaAs surface is highest by octadecanethiol methanol solution passivation, and it is 1.65 times higher than non-passivated. The surface stability test shows that the photoluminescence intensity of passivated GaAs surface do not deteriorate significantly after several days in air (PL intensity decreased by 22.1% within 30 days), which indicates that the self-assembled passivation layer of passivated GaAs surface has good stability.