Characterization of bio-hybrid interfaces under ambient conditions
type: CreativeWork
description: The topography, morphology, and chemistry of the surface of HVPE-grown n-GaN(0001) layers on c-sapphire/n-GaN(0001) samples were explored under various conditions before and after sputtering with 1 keV nitrogen N2 ions, followed by the functionalization with deionized water (H2O) and neutral L-cysteine (C3H7NO2S) molecules. Atomic force microscopy (AFM), low energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS) in ultra-high vacuum (UHV) and near-ambient-pressure (NAP) conditions were used for this investigation. Monochromatic X-ray 𝐴𝐴𝐴𝐴 𝐾𝐾𝐾𝐾 radi ation (ℎ𝜋𝜋 = 1486.7𝑒𝑒𝑉𝑉) was the exc itat ion source for the XPS experiments. The results obtained yielded information on the modifications occurring at the surface of the n-GaN(0001) layers upon N2+-sputtering and on the contact formation and interfacial chemical reactivity after exposure to H2O and L-cysteine, i.e., on the ensuing interactions and bonding mechanisms between H2O and L-cysteine molecules and the N2+-sputtered n-GaN(0001) surface. This provided a clue on the suitability, stability, and functionality of GaN-OH and GaN-SH groups, the primary links between the surface and inorganic, organic and biomolecules, and hence, on the potentiality of using GaN-based surfaces for electronic devices and biosensors. Experimental UHV-XPS spectra of C1s and O1s core-level (CL) transitions of the as-grown n-GaN(0001) surface revealed adsorbed adventitious carbon (C) and oxygen (O2) species, besides traces of Ga2O3 and Ga2Ox oxides. The surface AFM images and LEED patterns revealed that N2+-ion sputtering resulted in minimal surface damage and roughness, in addition to largely reducing the amount of adsorbed carbon species. The NAP-XPS spectra of the Ga 2p3/2 and Ga 3d5/2 photoemission lines of the N2+-sputtered n-GaN(0001)/H2O interface showed that the H2O molecules adsorbed on the n-GaN(0001) surface likely dissociated into a hydroxyl ion (OH−) and a proton (H+), which tend to combine with surface g…
abstract: The topography, morphology, and chemistry of the surface of HVPE-grown n-GaN(0001) layers on c-sapphire/n-GaN(0001) samples were explored under various conditions before and after sputtering with 1 keV nitrogen N2 ions, followed by the functionalization with deionized water (H2O) and neutral L-cysteine (C3H7NO2S) molecules. Atomic force microscopy (AFM), low energy electron diffraction (LEED), and X-ray photoelectron spectroscopy (XPS) in ultra-high vacuum (UHV) and near-ambient-pressure (NAP) conditions were used for this investigation. Monochromatic X-ray 𝐴𝐴𝐴𝐴 𝐾𝐾𝐾𝐾 radi ation (ℎ𝜋𝜋 = 1486.7𝑒𝑒𝑉𝑉) was the exc itat ion source for the XPS experiments. The results obtained yielded information on the modifications occurring at the surface of the n-GaN(0001) layers upon N2+-sputtering and on the contact formation and interfacial chemical reactivity after exposure to H2O and L-cysteine, i.e., on the ensuing interactions and bonding mechanisms between H2O and L-cysteine molecules and the N2+-sputtered n-GaN(0001) surface. This provided a clue on the suitability, stability, and functionality of GaN-OH and GaN-SH groups, the primary links between the surface and inorganic, organic and biomolecules, and hence, on the potentiality of using GaN-based surfaces for electronic devices and biosensors. Experimental UHV-XPS spectra of C1s and O1s core-level (CL) transitions of the as-grown n-GaN(0001) surface revealed adsorbed adventitious carbon (C) and oxygen (O2) species, besides traces of Ga2O3 and Ga2Ox oxides. The surface AFM images and LEED patterns revealed that N2+-ion sputtering resulted in minimal surface damage and roughness, in addition to largely reducing the amount of adsorbed carbon species. The NAP-XPS spectra of the Ga 2p3/2 and Ga 3d5/2 photoemission lines of the N2+-sputtered n-GaN(0001)/H2O interface showed that the H2O molecules adsorbed on the n-GaN(0001) surface likely dissociated into a hydroxyl ion (OH−) and a proton (H+), which tend to combine with surface g…
author: Ahmad, Mais
language: en
license: https://creativecommons.org/licenses/by/4.0/
date published: 2024
date modified: 2026-07-27T21:28:52Z
provider: Technische Universität Berlin
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Technische Universität Berlin

PropertyValue
property ID: DOI
value: 10.14279/depositonce-20099