Fabrication of porous aluminium nitride films on silicon substrate for a better overgrown layer

Abstract

In this work, properties of aluminium nitride films grown on Si substrates with two different thicknesses were investigated. From our observations, the aluminium nitride film with the thickness of ∼122 nm exhibited a better characteristic than the aluminium nitride film grown at ∼80 nm. Further, the sample with thicker aluminium nitride film was fabricated into porous structures using photoelectrochemical etching with a diluted sodium hydroxide electrolyte. As witnessed under field emission scanning electron microscopy, the formation of porous structures can be observed even though they are few and not uniformly distributed on the surface. Moreover, defect clusters and grain boundaries in the porous sample disappeared after the etching process, thus giving a narrower peak in X-ray diffraction rocking curve measurement. This work is a starting point towards establishing the technology of fabricating porous aluminium nitride to make it useful as a template for the subsequent growth.

Keywords:

• Porous AlN
• Photoelectrochemical etching
• NaOH electrolyte
• Surface defect clusters
• XRD FWHM

Acknowledgements

This work was conducted under Exploratory Research Grant Scheme (ERGS) (account number: 203/PFIZIK/6730095), The World Academy of Sciences (TWAS) Research Grant (reference: 11-122RG/MSN/AS_C; UNESCO FR: 3240262661) and Research University Individu (RUI) (account number: 1001/PFIZIK/811231). Support from the technical staffs is highly appreciated.