Electrical properties of polycrystalline GaN films functionalized with cysteine and stabilization of GaN nanoparticles in aqueous media

GaN was synthesized onto sapphire substrates by chemical vapor deposition, reacting gallium, ammonium chloride and ammonia. The polycrystalline films were immersed in glycine, aspartic acid and cysteine solutions. Cysteine chemisorbed onto GaN films produced detectable changes in conductivity, mobility and Hall coefficient indicating that GaN is capable of detecting and reacting with thiolate groups, which was confirmed by X-ray photoelectron spectroscopy. The Cys-GaN film solution was adjusted to pH 10, upon which the GaN nanoparticles were transferred to the aqueous phase forming a suspension stable for seven days. The alkaline colloid was then further adjusted down to pH 3 retaining stability for three days. The GaN colloid obtained represents a suitable medium to study GaN properties for biological applications.

Graphical abstractThe functionalization of GaN films with glycine, aspartic acid and cysteine was attempted. The electrical properties changed due to functionalization of GaN with the thiol group of cysteine. Under alkaline conditions the cysteine solution was capable to transfer GaN crystallites from the film (a) to the liquid phase (b).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► GaN functionalization with glycine, aspartic acid and glycine was attempted. ► The electrical properties of GaN films changed when exposed to the thiol group of cysteine. ► Cys alkaline solution produced an aqueous GaN colloidal suspension.