title: Photochemical Modification of Single Crystalline GaN Film Using n-Alkene with Different Carbon Chain Lengths as Biolinker.
abstract: As a potential material for biosensing applications, gallium nitride (GaN) films have attracted remarkable attention. In order to construct GaN biosensors, a corresponding immobilization of biolinkers is of great importance in order to render a surface bioactive. In this work, two kinds of n-alkenes with different carbon chain lengths, namely allylamine protected with trifluoroacetamide (TFAAA) and 10-aminodec-1-ene protected with trifluoroacetamide (TFAAD), were used to photochemically functionalize single crystalline GaN films. The successful linkage of both TFAAA and TFAAD to the GaN films is confirmed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) measurement. With increased UV illumination time, the intensity of the secondary ions corresponding to the linker molecules initially increases and subsequently decreases in both cases. Based on the SIMS measurements, the maximum coverage of TFAAA is achieved after 14 h of UV illumination, while only 2 h is required in the case of TFAAD to reach the situation of a fully covered GaN surface. This finding leads to the conclusion that the reaction rate of TFAAD is significantly higher compared to TFAAA. Measurements by atomic force microscopy (AFM) indicate that the coverage of GaN films by a TFAAA layer leads to an increased surface roughness. The atomic terraces, which are clearly observable for the pristine GaN films, disappear once the surface is fully covered by a TFAAA layer. Such TFAAA layers will feature a homogeneous surface topography even for reaction times of 24 h. In contrast to this, TFAAD shows strong cross-polymerization on the surface, this is confirmed by optical microscopy. These results demonstrate that TFAAA is a more suitable candidate as biolinker in context of the GaN surfaces due to its improved controllability.
authors.affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Wang
authors.affiliation: Institute of Materials Engineering, University of Siegen , Paul-Bonatz-Str. 9-11, 57076 Siegen, Germany.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhuang
authors.affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Huang
authors.affiliation: Institute of Materials Engineering, University of Siegen , Paul-Bonatz-Str. 9-11, 57076 Siegen, Germany.
authors.forename: Steffen
authors.initials: S
authors.lastname: Heuser
authors.affiliation: Institute of Materials Engineering, University of Siegen , Paul-Bonatz-Str. 9-11, 57076 Siegen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schlemper
authors.affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China.
authors.forename: Zhaofeng
authors.initials: Z
authors.lastname: Zhai
authors.affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China.
authors.forename: Baodan
authors.initials: B
authors.lastname: Liu
authors.affiliation: Institute of Materials Engineering, University of Siegen , Paul-Bonatz-Str. 9-11, 57076 Siegen, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Staedler
authors.affiliation: Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences , Wenhua Road 72, 110016 Shenyang, China.|Institute of Materials Engineering, University of Siegen , Paul-Bonatz-Str. 9-11, 57076 Siegen, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Jiang