Photochemical Functionalization of Gallium Nitride Thin Films with Molecular and Biomolecular Layers

Abstract

We demonstrate that photochemical functionalization can be used to functionalize and photopattern the surface of gallium nitride crystalline thin films with well-defined molecular and biomolecular layers. GaN(0001) surfaces exposed to a hydrogen plasma will react with organic molecules bearing an alkene (C=C) group when illuminated with 254 nm light. Using a bifunctional molecule with an alkene group at one end and a protected amine group at the other, this process can be used to link the alkene group to the surface, leaving the protected amine exposed. Using a simple contact mask, we demonstrate the ability to directly pattern the spatial distribution of these protected amine groups on the surface with a lateral resolution of <12 mum. After deprotection of the amines, single-stranded DNA oligonucleotides were linked to the surface using a bifunctional cross-linker. Measurements using fluorescently labeled complementary and noncomplementary sequences show that the DNA-modified GaN surfaces exhibit excellent selectivity, while repeated cycles of hybridization and denaturation in urea show good stability. These results demonstrate that photochemical functionalization can be used as an attractive starting point for interfacing molecular and biomolecular systems with GaN and other compound semiconductors.

Novel semiconductor materials for the development of chemical sensors and biosensors: A review

“…GaN [54][55][56][57][58][59][60] InN [61] Diamond [62,63] Other electroanalytical applications Diamond [64][65][66][67][68][69][70][71][72][73][74] Bio-electrochemical applications Diamond [75][76][77] GaN [78][79][80] Electrocatalysis Diamond [81][82][83] Shear mode acoustic wave biosensors…”

Comparison of the Stability of Functionalized GaN and GaP

“…[9] The inherent need to reduce the total surface energy drives the natural reduction of dangling bonds [10,11] which-in the presence of organic functional groups-form chemically adsorbed layers. [12] Many groups have explored surface adsorbates such as thiols, [13] silanes, [14] phosphonic acids, [15] and carboxylic acids [16] as ways to modulate the surface properties. Thiols, perhaps the most widely reported, bind directly to metallic or low-valence atoms centers.…”

A review of in situ surface functionalization of gallium nitride via beaker wet chemistry

“…16,17 Furthermore, DNA binding olefin has been placed on the material by photochemical activation. 18 GaN nanowire surfaces have also been coated by aluminum, titanium, and silicon oxides using an atomic layer deposition technique to provide enhanced binding prior to chemical modification. 19 Self-assembled molecules of alkylphosphonic acid are also shown to readily form monolayers on the GaN films.…”