Mid-IR plasmonic compound with gallium oxide toplayer formed by GaSb oxidation in water

The oxidation of GaSb in aqueous environments has gained interest by the advent of plasmonic antimonide-based compound semiconductors for molecular sensing applications. This work focuses on quantifying the GaSb–water reaction kinetics by studying a model compound system consisting of a 50 nm thick GaSb layer on a 1000 nm thick highly Si-doped epitaxial grown InAsSb layer. Tracing of phonon modes by Raman spectroscopy over 14 h of reaction time shows that within 4 h, the 50 nm of GaSb, opaque for visible light, transforms to a transparent material. Energy-dispersive x-ray spectroscopy shows that the reaction leads to antimony depletion and oxygen incorporation. The final product is a gallium oxide. The good conductivity of the highly Si-doped InAsSb and the absence of conduction states through the oxide are demonstrated by tunneling atomic force microscopy. Measuring the reflectivity of the compound layer structure from 0.3 to 20 μm and fitting of the data by the transfer-matrix method allows us to determine a refractive index value of 1.6 ± 0.1 for the gallium oxide formed in water. The investigated model system demonstrates that corrosion, i.e. antimony depletion and oxygen incorporation, transforms the narrow band gap material GaSb into a gallium oxide transparent in the range from 0.3 to 20 μm

Optical detection and spatial modulation of mid-infrared surface plasmon polaritons in a highly doped semiconductor

Highly doped semiconductors (HDSCs) are promising candidates for plasmonic applications in the mid-infrared (MIR) spectral range. This work examines a recent addition to the HDSC family, the dilute nitride alloy In(AsN). Post-growth hydrogenation of In(AsN) creates a highly conducting channel near the surface and a surface plasmon polariton detected by attenuated total reflection techniques. The suppression of plasmonic effects following a photo-annealing of the semiconductor is attributed to the dissociation of the N-H bond. This offers new routes for direct patterning of MIR plasmonic structures by laser writing

Surface functionalization of plasmonic III-V semiconductors for surface-enhanced vibrational spectroscopy

Cette thèse traite de la fonctionnalisation de surface des résonateurs plasmonique à base de semi-conducteur III-V en utilisant de l’acide phosphonique pour la spectroscopie vibrationnelle exaltée permettant d'identifier des quantités infimes de molécules. Le premier chapitre décrit les fondements théoriques de la spectroscopie vibrationnelle exaltée. En comparant les propriétés plasmoniques du semi-conducteur dégénéré InAs(Sb):Si et des métaux, ici l’or et le gallium, on trouve que l’InAs(Sb):Si est particulièrement adapté à la spectroscopie infrarouge exaltée (SEIRA) et que le gallium est adapté à la spectroscopie Raman exaltée (SERS). Les deux matériaux plasmoniques alternatifs surpassent théoriquement l'or dans leurs gammes spectrales respectives. Néanmoins, l'or et son inertie chimique restent intéressants pour permettre la spectroscopie vibrationnelle exaltée dans différents environnements chimiques.Dans le deuxième chapitre on démontre que l’InAs(Sb):Si est chimiquement stable dans l'eau, contrairement au GaSb. Une structure en couches composites de GaSb/InAsSb:Si a été utilisée pour montrer que la déplétion de l'antimoine et l'incorporation d'oxygène à l'interface GaSb-eau transforment, en un peu moins de 14 h, 50 nm de GaSb cristallin en un oxyde de gallium. Cet oxyde de gallium a un indice de réfraction moyen-IR de l'ordre de n=1,6 ce qui est environ la moitié de la valeur de l'indice de réfraction du GaSb dans le moyen-IR.Dans le troisième chapitre, on démontre que cette modification de l'indice de réfraction lors de l'oxydation peut être exploitée pour décaler la résonance plasmonique localisée des réseaux InAsSb:Si sur des substrats GaSb dans la plage de 5 µm à 20 µm par formation d’un piédestal.Dans le chapitre 4 est présenté le contrôle de la liaison chimique des molécules organiques avec la fine couche d'oxyde natif à la surface du semi-conducteur III-V. L’attachement de ces molécules sur l’oxyde de surface ouvre la voie à des applications bio-photoniques utilisant des semi-conducteurs améliorés par des résonateurs plasmoniques.Dans le chapitre 5 est décrit deux stratégies différentes pour combiner des résonateurs plasmoniques à base de III-V avec des circuits micro-fluidiques. Ces résultats démontrent que des applications lab-on-the-chip basées sur des semi-conducteurs III-V sont possibles.Enfin, la possibilité d'intégrer des nanoparticules de Gallium plasmoniques sur des semi-conducteurs III-V pour combiner les méthodes SEIRA et SERS est présentée au chapitre 6.This thesis deals with the surface functionalization of nanostructured plasmonic III-V semiconductors for surface-enhanced vibrational spectroscopy relevant to identify minute amounts of analyte molecules.The first chapter outlines the theoretical foundations of surface-enhanced vibrational spectroscopy based on plasmonics. Comparing the plasmonic properties of the degenerate semiconductor InAs(Sb):Si and of metals, here gold and gallium, it is found that the degenerate semiconductor is especially suited for surface-enhanced infrared (SEIRA) spectroscopy and that gallium with its plasmonic potential in the UV-VIS range is apt for surface-enhanced Raman spectroscopy (SERS). Both alternative plasmonic materials theoretically outperform gold in their respective spectral ranges. Nevertheless, gold and its chemical inertness remain interesting for enabling plasmonic enhanced vibrational spectroscopy in different chemical environments. The influence of aqueous environments on the material properties of III-V semiconductors is addressed in the second and in the third chapter. It is found that InAs(Sb):Si is chemical stable in water, but GaSb is not. A GaSb/InAsSb:Si compound layer structure was used to demonstrate that the depletion of antimony and the incorporation of oxygen at the GaSb-water interface transform 50 nm of crystalline GaSb to a gallium oxide in less than 14 hours. The gallium oxide has a mid-IR refractive index in the order of n=1.6 and thus less than half of the value of the mid-IR refractive index of GaSb. This change in refractive index upon oxidation can be exploited to blue-shift the localized plasmonic resonance of InAsSb:Si gratings on GaSb-substrates in the range from 5 µm to 20 µm by pedestal formation.In Chapter 4, the controlled chemical bonding of organic molecules to the approximately 3 nm thin native oxide layer of III-V semiconductor surfaces by phosphonic acid chemistry is presented. This paves the way for plasmonic enhanced all-semiconductor mid-IR biophotonic applications. In chapter 5, two different, but equally successful strategies to combine III-V based plasmonic resonators with microfluidic circuits are described. These results demonstrate that lab-on-the-chip applications based on III-V semiconductors are possible. Finally, the possibility to integrate plasmonic Gallium nanoparticles onto the III-V material platform for a potential combination of SEIRA and SERS applications is presented in chapter 6

Fonctionnalisation de surface de résonateurs plasmoniques à base de semi-conducteur III-V pour la spectroscopie vibrationnelle exaltée

This thesis deals with the surface functionalization of nanostructured plasmonic III-V semiconductors for surface-enhanced vibrational spectroscopy relevant to identify minute amounts of analyte molecules.The first chapter outlines the theoretical foundations of surface-enhanced vibrational spectroscopy based on plasmonics. Comparing the plasmonic properties of the degenerate semiconductor InAs(Sb):Si and of metals, here gold and gallium, it is found that the degenerate semiconductor is especially suited for surface-enhanced infrared (SEIRA) spectroscopy and that gallium with its plasmonic potential in the UV-VIS range is apt for surface-enhanced Raman spectroscopy (SERS). Both alternative plasmonic materials theoretically outperform gold in their respective spectral ranges. Nevertheless, gold and its chemical inertness remain interesting for enabling plasmonic enhanced vibrational spectroscopy in different chemical environments. The influence of aqueous environments on the material properties of III-V semiconductors is addressed in the second and in the third chapter. It is found that InAs(Sb):Si is chemical stable in water, but GaSb is not. A GaSb/InAsSb:Si compound layer structure was used to demonstrate that the depletion of antimony and the incorporation of oxygen at the GaSb-water interface transform 50 nm of crystalline GaSb to a gallium oxide in less than 14 hours. The gallium oxide has a mid-IR refractive index in the order of n=1.6 and thus less than half of the value of the mid-IR refractive index of GaSb. This change in refractive index upon oxidation can be exploited to blue-shift the localized plasmonic resonance of InAsSb:Si gratings on GaSb-substrates in the range from 5 µm to 20 µm by pedestal formation.In Chapter 4, the controlled chemical bonding of organic molecules to the approximately 3 nm thin native oxide layer of III-V semiconductor surfaces by phosphonic acid chemistry is presented. This paves the way for plasmonic enhanced all-semiconductor mid-IR biophotonic applications. In chapter 5, two different, but equally successful strategies to combine III-V based plasmonic resonators with microfluidic circuits are described. These results demonstrate that lab-on-the-chip applications based on III-V semiconductors are possible. Finally, the possibility to integrate plasmonic Gallium nanoparticles onto the III-V material platform for a potential combination of SEIRA and SERS applications is presented in chapter 6.Cette thèse traite de la fonctionnalisation de surface des résonateurs plasmonique à base de semi-conducteur III-V en utilisant de l’acide phosphonique pour la spectroscopie vibrationnelle exaltée permettant d'identifier des quantités infimes de molécules. Le premier chapitre décrit les fondements théoriques de la spectroscopie vibrationnelle exaltée. En comparant les propriétés plasmoniques du semi-conducteur dégénéré InAs(Sb):Si et des métaux, ici l’or et le gallium, on trouve que l’InAs(Sb):Si est particulièrement adapté à la spectroscopie infrarouge exaltée (SEIRA) et que le gallium est adapté à la spectroscopie Raman exaltée (SERS). Les deux matériaux plasmoniques alternatifs surpassent théoriquement l'or dans leurs gammes spectrales respectives. Néanmoins, l'or et son inertie chimique restent intéressants pour permettre la spectroscopie vibrationnelle exaltée dans différents environnements chimiques.Dans le deuxième chapitre on démontre que l’InAs(Sb):Si est chimiquement stable dans l'eau, contrairement au GaSb. Une structure en couches composites de GaSb/InAsSb:Si a été utilisée pour montrer que la déplétion de l'antimoine et l'incorporation d'oxygène à l'interface GaSb-eau transforment, en un peu moins de 14 h, 50 nm de GaSb cristallin en un oxyde de gallium. Cet oxyde de gallium a un indice de réfraction moyen-IR de l'ordre de n=1,6 ce qui est environ la moitié de la valeur de l'indice de réfraction du GaSb dans le moyen-IR.Dans le troisième chapitre, on démontre que cette modification de l'indice de réfraction lors de l'oxydation peut être exploitée pour décaler la résonance plasmonique localisée des réseaux InAsSb:Si sur des substrats GaSb dans la plage de 5 µm à 20 µm par formation d’un piédestal.Dans le chapitre 4 est présenté le contrôle de la liaison chimique des molécules organiques avec la fine couche d'oxyde natif à la surface du semi-conducteur III-V. L’attachement de ces molécules sur l’oxyde de surface ouvre la voie à des applications bio-photoniques utilisant des semi-conducteurs améliorés par des résonateurs plasmoniques.Dans le chapitre 5 est décrit deux stratégies différentes pour combiner des résonateurs plasmoniques à base de III-V avec des circuits micro-fluidiques. Ces résultats démontrent que des applications lab-on-the-chip basées sur des semi-conducteurs III-V sont possibles.Enfin, la possibilité d'intégrer des nanoparticules de Gallium plasmoniques sur des semi-conducteurs III-V pour combiner les méthodes SEIRA et SERS est présentée au chapitre 6

Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

Tailored plasmonic nanoantennas are neededfor diverse applications, among those sensing. Surfaceenhancedinfrared absorption (SEIRA) spectroscopy usingadapted nanoantenna substrates is an efficient techniquefor the selective detection of molecules by their vibrationalspectra, even in small quantity. Highly doped semiconductorshave been proposed as innovative materials forplasmonics, especially for more flexibility concerning thetargeted spectral range. Here, we report on rectangularshaped,highly Si-doped InAsSb nanoantennas sustainingpolarization switchable longitudinal and transverseplasmonic resonances in the mid-infrared. For small arrayperiodicities, the highest reflectance intensity is obtained.Large periodicities can be used to combine localized surfaceplasmon resonances (SPR) with array resonances,as shown in electromagnetic calculations. The nanoantennaarrays can be efficiently used for broadband SEIRAspectroscopy, exploiting the spectral overlap between thelarge longitudinal or transverse plasmonic resonancesand narrow infrared active absorption features of an analytemolecule. We demonstrate an increase of the vibrationalline intensity up to a factor of 5.7 of infrared-activeabsorption features of vanillin in the fingerprint spectralregion, yielding enhancement factors of three to fourorders of magnitude. Moreover, an optimized readout forSPR sensing is proposed based on slightly overlappinglongitudinal and transverse localized SPR

Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA) spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR) with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR

Microfluidic surface-enhanced infrared spectroscopy with semiconductor plasmonics for the fingerprint region

International audienc

Spectroscopic investigation of localized surface plasmon resonator structure by infrared nanoscopy near the plasma frequency

International audienc

Pedestal formation of all-semiconductor gratings through GaSb oxidation for mid-IR plasmonics

Mid-IR localized surface plasmon resonances (LSPR) have been demonstrated in nanoribbons of highly Si-doped InAsSb alloys on GaSb substrates. We show that the slow, steady and selective oxidation of GaSb in water leads to an all-semiconductor mid-IR pedestal configuration consisting of highly doped InAsSb plasmonic resonators on top of GaSb pedestals embedded in an amorphous oxide layer. The homogeneity of the pedestal structure is imaged with an attenuated-total reflection Fourier transform infrared (ATR-FTIR) microscope by measuring around the plasmonic excitation at the plasma wavelength of 5.5 mu m. As the plasmonic properties are influenced by modifications of the surrounding medium, we show for all-semiconductor gratings with defined doping level and defined grating geometry, that the GaSb oxidation process allows post-fabrication targeting of mid-IR plasmonic resonances to cover the mid-IR range from 5 to 20 mu m. Additionally, the pedestal formation reduces the refractive index mismatch between the two interfaces of the plasmonic resonators which allows the exploitation of a second plasmonic peak and which favors plasmonic field enhancement at the top (air-) side of the structure relevant for enhanced molecular vibration spectroscopy